Giải sách bài tập Khoa học tự nhiên 7

<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLt7oJ6fnjHC3HQ10W37nx_YPqf1g7xwUrBgRPE2E4azc0ibHVJvRjqwSCHVbgtdfHixLT5iP24WynOhgasMuNa44et87nVq1hISbMZIeZTOYcRJXpUE_KlJ9yJWa7YHuQmCV2z_WRNFNKxXXk5pw5gycPyvcUN32nl-p29xhf5jW2okW_jHzXHy4Zomc/s184/K.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="164" data-original-width="184" height="164" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLt7oJ6fnjHC3HQ10W37nx_YPqf1g7xwUrBgRPE2E4azc0ibHVJvRjqwSCHVbgtdfHixLT5iP24WynOhgasMuNa44et87nVq1hISbMZIeZTOYcRJXpUE_KlJ9yJWa7YHuQmCV2z_WRNFNKxXXk5pw5gycPyvcUN32nl-p29xhf5jW2okW_jHzXHy4Zomc/s1600/K.jpg" width="184" /></a><br /><br /><span style="color: red; font-size: large;"><b><img src="https://loigiaihay.com/themes/images/star.png" /> Chủ đề 1. Nguyên tử - Nguyên tố hóa học - Sơ lược về bảng tuần hoàn các nguyên tố hóa học<br /></b></span><a href="https://khanhnhusaigon.blogspot.com/2023/09/bai-2-nguyen-tu-trang-6-7-sbt-khoa-hoc.html" target="_blank"><span style="font-size: medium;"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />1. Bài 2. Nguyên tử</span><br /></a><span style="font-size: medium;"><a href="https://khanhnhusaigon.blogspot.com/2023/09/bai-3-nguyen-to-hoa-hoc-trang-8-9-10.html" target="_blank"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />2. Bài 3. Nguyên tố hóa học</a></span><div><a href="https://khanhnhusaigon.blogspot.com/2023/09/bai-4-so-luoc-ve-bang-tuan-hoan-cac.html" target="_blank"><span style="font-size: medium;"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />3. Bài 4. Sơ lược về bảng tuần hoàn các nguyên tố hóa học</span><br /></a><br /><span style="color: red; font-size: large;"><b><img src="https://loigiaihay.com/themes/images/star.png" /> Chủ đề 2. Phân tử<br /></b></span><a href="https://khanhnhusaigon.blogspot.com/2023/09/bai-5-phan-tu-on-chat-hop-chat-trang-14.html" target="_blank"><span style="font-size: medium;"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />1. Bài 5. Phân tử - Đơn chất - Hợp chất</span><br /></a><span style="font-size: medium;"><a href="https://khanhnhusaigon.blogspot.com/2023/09/bai-6-gioi-thieu-ve-lien-ket-hoa-hoc_28.html" target="_blank"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />2. Bài 6. Giới thiệu về liên kết hóa học</a></span></div><div><a href="https://khanhnhusaigon.blogspot.com/2023/09/bai-7-hoa-tri-va-cong-thuc-hoa-hoc_28.html" target="_blank"><span style="font-size: medium;"><img src="https://loigiaihay.com/themes/images/tamgiac.png" /></span><span style="font-size: large;">3. Bài 7. Hóa trị và công thức hóa học</span></a></div><div><br /><span style="color: red; font-size: large;"><b><img src="https://loigiaihay.com/themes/images/star.png" /> Chủ đề 3. Tốc độ<br /></b></span><a href="https://khanhnhusaigon.blogspot.com/2023/09/bai-8-toc-o-chuyen-ong-trang-26-27-sbt.html" target="_blank"><span style="font-size: medium;"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />1. Bài 8. Tốc độ chuyển động</span><br /></a><span style="font-size: medium;"><a href="https://khanhnhusaigon.blogspot.com/2023/09/bai-9-o-thi-quang-uong-thoi-gian-trang_28.html" target="_blank"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />2. Bài 9. Đồ thị quãng đường - thời gian</a></span></div><div><span style="font-size: medium;"><a href="https://khanhnhusaigon.blogspot.com/2023/09/bai-10-o-toc-o-trang-31-32-33-sbt-khoa.html" target="_blank"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />3. Bài 10. Đo tốc độ<br /></a><a href="https://khanhnhusaigon.blogspot.com/2023/09/bai-11-toc-o-va-toan-giao-thong-trang_28.html" target="_blank"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />4. Bài 11. Tốc độ và an toàn giao thông<br /></a><br /><a href="https://loigiaihay.com/chu-de-4-am-thanh-e27240.html"><img src="https://loigiaihay.com/themes/images/star.png" /> Chủ đề 4. Âm thanh</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-12-mo-ta-song-am-trang-37-38-chan-troi-sang-tao-a115373.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />1. Bài 12. Mô tả sóng âm</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-13-do-to-va-do-cao-cua-am-trang-39-40-41-chan-troi-sang-tao-a115378.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />2. Bài 13. Độ to và độ cao của âm</a><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-14-phan-xa-am-trang-42-43-chan-troi-sang-tao-a115384.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />3. Bài 14. Phản xạ âm</a><br /><br /><a href="https://loigiaihay.com/chu-de-5-anh-sang-e27241.html"><img src="https://loigiaihay.com/themes/images/star.png" /> Chủ đề 5. Ánh sáng</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-15-anh-sang-tia-sang-trang-44-45-chan-troi-sang-tao-a115387.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />1. Bài 15. Ánh sáng, tia sáng</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-16-su-phan-xa-anh-sang-trang-46-47-chan-troi-sang-tao-a115482.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />2. Bài 16. Sự phản xạ ánh sáng</a><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-17-anh-cua-mot-vat-tao-boi-guong-phang-trang-48-49-chan-troi-sang-tao-a115489.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />3. Bài 17. Ảnh của một vật tạo bởi gương phẳng</a><br /><br /><a href="https://loigiaihay.com/chu-de-6-tu-e27242.html"><img src="https://loigiaihay.com/themes/images/star.png" /> Chủ đề 6. Từ</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-18-nam-cham-chan-troi-sang-tao-a115497.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />1. Bài 18. Nam châm</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-19-tu-truong-trang-52-53-chan-troi-sang-tao-a115499.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />2. Bài 19. Từ trường</a><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-19-tu-truong-trai-dat-su-dung-la-ban-trang-54-55-chan-troi-sang-tao-a115501.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />3. Bài 20. Từ trường Trái Đất - Sử dụng la bàn</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-21-nam-cham-dien-trang-56-57-chan-troi-sang-tao-a115502.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />4. Bài 21. Nam châm điện</a><br /><br /><a href="https://loigiaihay.com/chu-de-7-trao-doi-chat-va-chuyen-hoa-nang-luong-o-sinh-vat-e27332.html"><img src="https://loigiaihay.com/themes/images/star.png" /> Chủ đề 7. Trao đổi chất và chuyển hóa năng lượng ở sinh vật</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-30-trao-doi-nuoc-va-cac-chat-dinh-duong-o-dong-vat-trang-74-75-76-khoa-hoc-tu-nhien-7-chan-troi-sang-tao-a136446.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />1. Bài 30. Trao đổi nước và các chất dinh dưỡng ở động vật</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-31-thuc-hanh-chung-minh-than-van-chuyen-nuoc-va-la-thoat-hoi-nuoc-trang-77-78-khoa-hoc-tu-nhien-7-chan-troi-sang-tao-a136454.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />2. Bài 31. Thực hành chứng minh thân vận chuyển nước và lá thoát hơi nước</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-22-vai-tro-cua-trao-doi-chat-va-chuyen-hoa-nang-luong-o-sinh-vat-sbt-trang-58-59-khoa-hoc-tu-nhien-7-chan-troi-sang-tao-a115306.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />3. Bài 22: Vai trò của trao đổi chất và chuyển hóa năng lượng ở sinh vật</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-23-quang-hop-o-thuc-vat-sbt-trang-60-61-khoa-hoc-tu-nhien-7-chan-troi-sang-tao-a115308.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />4. Bài 23: Quang hợp ở thực vật</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-24-thuc-hanh-chung-minh-quang-hop-o-cay-xanh-sbt-trang-62-63-khoa-hoc-tu-nhien-7-chan-troi-sang-tao-a115311.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />5. Bài 24: Thực hành chứng minh quang hợp ở cây xanh</a><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-25-ho-hap-o-thuc-vat-sbt-trang-64-65-khoa-hoc-tu-nhien-7-chan-troi-sang-tao-a115314.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />6. Bài 25: Hô hấp tế bào</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-26-thuc-hanh-ve-ho-hap-te-bao-o-thuc-vat-thong-qua-su-nay-mam-cua-hat-sbt-trang-66-67-khoa-hoc-tu-nhien-7-chan-troi-sang-tao-a115317.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />7. Bài 26: Thực hành về hô hấp tế bào ở thực vật thông qua sự nảy mầm của hạt</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-27-trao-doi-khi-o-sinh-vat-sbt-trang-68-69-khoa-hoc-tu-nhien-7-chan-troi-sang-tao-a115319.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />8. Bài 27: Trao đổi khí ở sinh vật</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-28-vai-tro-cua-nuoc-va-cac-chat-dinh-duong-doi-voi-co-the-sinh-vat-sbt-trang-70-71-khoa-hoc-tu-nhien-7-chan-troi-sang-tao-a115320.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />9. Bài 28: Vai trò của nước và các chất dinh dưỡng đối với cơ thể sinh vật</a><br /><a href="https://loigiaihay.com/giai-sbt-khoa-hoc-tu-nhien-7-bai-29-trao-doi-nuoc-va-cac-chat-dinh-duong-o-thuc-vat-sbt-trang-72-73-khoa-hoc-tu-nhien-7-chan-troi-sang-tao-a115322.html"><img src="https://loigiaihay.com/themes/images/tamgiac.png" />10. Bài 29: Trao đổi nước và các chất dinh dưỡng ở thực vật</a></span></div><div class="separator" style="clear: both; text-align: center;"><br /></div><br />

Giải sách bài tập Khoa học tự nhiên 7

Chủ đề 1. Nguyên tử - Nguyên tố hóa học - Sơ lược về bảng tuần hoàn các nguyên tố hóa học 1. Bài 2. Nguyên tử 2. Bài 3. Nguyên tố hóa học 3...

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Bài 10. Đo tốc độ trang 31, 32, 33 SBT Khoa học tự nhiên 7

<div class="box-question top20" id="sub-question-1" style="background-color: white; border-bottom: 1px dotted rgb(225, 225, 225); font-family: OpenSans, Tahoma, Helvetica, sans-serif; font-size: 18px; height: auto; line-height: 26px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 20px !important; padding: 0px; text-align: justify; width: calc(100% - 40px) !important;"><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="color: #2888e1; font-family: OpenSansBold; margin: 0px; padding: 0px;">10.1</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Để đo tốc độ của một người chạy cự ly ngắn, ta cần những dụng cụ đo nào?</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">A. Thước cuộn và đồng hồ bấm giây.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">B. Thước thẳng và đồng hồ treo tường.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">C. Đồng hồ đo thời gian hiện số kết nối với cổng quang điện.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">D. Cổng quang điện và thước cuộn.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Phương pháp giải:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+ Để đo tốc độ của một vật diễn ra trong một khoảng thời gian dài (trung bình), người ta thường sử dụng đồng hồ bấm giây.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+ Để đo tốc độ của một vật diễn ra trong một khoảng thời gian ngắn, người ta thường dùng cổng quang điện kết nối với đồng hồ đo thời gian hiện số thay cho đồng hồ bấm giây.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Lời giải chi tiết:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Chọn A.</p></div><div class="box-question top20" id="sub-question-2" style="background-color: white; border-bottom: 1px dotted rgb(225, 225, 225); font-family: OpenSans, Tahoma, Helvetica, sans-serif; font-size: 18px; height: auto; line-height: 26px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 20px !important; padding: 0px; text-align: justify; width: calc(100% - 40px) !important;"><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="color: #2888e1; font-family: OpenSansBold; margin: 0px; padding: 0px;">10.2</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Trong phòng thí nghiệm, người ta thường sử dụng những dụng cụ đo nào để đo tốc độ của các vật chuyển động nhanh và có kích thước nhỏ?</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">A. Thước, cổng quang điện và đồng hồ bấm giây.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">B. Thước, đồng hồ đo thời gian hiện số kết nối với cổng quang điện.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">C. Thước và đồng hồ đo thời gian hiện số.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">D. Cổng quang điện và đồng hồ bấm giây.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Phương pháp giải:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+ Để đo tốc độ của một vật diễn ra trong một khoảng thời gian dài (trung bình), người ta thường sử dụng đồng hồ bấm giây.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+ Để đo tốc độ của một vật diễn ra trong một khoảng thời gian ngắn, người ta thường dùng cổng quang điện kết nối với đồng hồ đo thời gian hiện số thay cho đồng hồ bấm giây.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Lời giải chi tiết:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Chọn B.</p></div><div class="box-question top20" id="sub-question-3" style="background-color: white; border-bottom: 1px dotted rgb(225, 225, 225); font-family: OpenSans, Tahoma, Helvetica, sans-serif; font-size: 18px; height: auto; line-height: 26px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 20px !important; padding: 0px; text-align: justify; width: calc(100% - 40px) !important;"><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="color: #2888e1; font-family: OpenSansBold; margin: 0px; padding: 0px;">10.3</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Trong một thí nghiệm đo tốc độ của xe đồ chơi chạy pin, khi cho xe chạy qua hai cổng quang điện cách nhau 20 cm thì thời gian xe chạy qua hai cổng quang điện được hiển thị trên đồng hồ là 1,02 s. Tính tốc độ chuyển động của xe.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Phương pháp giải:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Biểu thức tính tốc độ: <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac></math>" id="MathJax-Element-1-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-1" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-2" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-3" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-4" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-5" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-6" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-7" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) v: tốc độ chuyển động của vật (m/s)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) s: quãng đường đi được của vật (m)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) t: thời gian đi được quãng đường s của vật (s)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Đổi đơn vị độ dài: 1 cm = <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>1</mn><mrow class="MJX-TeXAtom-ORD"><mn>100</mn></mrow></mfrac><mi>m</mi></math>" id="MathJax-Element-2-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-8" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-9" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mfrac" id="MJXc-Node-10" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 1.202em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.276em; width: 1.7em;"><span class="mjx-mn" id="MJXc-Node-11" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span></span><span class="mjx-denominator" style="bottom: -0.591em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 1.7em;"><span class="mjx-texatom" id="MJXc-Node-12" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-13" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-14" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">100</span></span></span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 1.202em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.32em; margin: 0px; padding: 0px; vertical-align: -0.418em; width: 0px;"></span></span><span class="mjx-mi" id="MJXc-Node-15" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">m</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>1</mn><mrow class="MJX-TeXAtom-ORD"><mn>100</mn></mrow></mfrac><mi>�</mi></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Lời giải chi tiết:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Tóm tắt:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">s = 20 cm = <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>20</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>100</mn></mrow></mfrac><mi>m</mi><mo>=</mo><mn>0</mn><mo>,</mo><mn>2</mn><mi>m</mi></math>" id="MathJax-Element-3-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-16" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-17" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mfrac" id="MJXc-Node-18" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 1.202em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.298em; width: 1.7em;"><span class="mjx-texatom" id="MJXc-Node-19" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-20" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-21" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">20</span></span></span></span></span><span class="mjx-denominator" style="bottom: -0.591em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 1.7em;"><span class="mjx-texatom" id="MJXc-Node-22" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-23" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-24" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">100</span></span></span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 1.202em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.336em; margin: 0px; padding: 0px; vertical-align: -0.418em; width: 0px;"></span></span><span class="mjx-mi" id="MJXc-Node-25" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">m</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-26" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-27" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">0</span></span><span class="mjx-mo" id="MJXc-Node-28" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn MJXc-space1" id="MJXc-Node-29" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.167em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">2</span></span><span class="mjx-mi" id="MJXc-Node-30" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">m</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>20</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>100</mn></mrow></mfrac><mi>�</mi><mo>=</mo><mn>0</mn><mo>,</mo><mn>2</mn><mi>�</mi></math></span></span><a href="file:///C:/Users/HP/Documents/SBT/KHTN%207/CTST/bai10ly7%20(10%20b%C3%A0i).docx#_msocom_1" style="color: #336699; margin: 0px; outline: 0px; padding: 0px; text-decoration-line: none;">[1]</a> </p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">t =  1,02 s</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">v = ?</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Lời giải:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Tốc độ chuyển động của xe là:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>0</mn><mo>,</mo><mn>2</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>1</mn><mo>,</mo><mn>02</mn></mrow></mfrac><mo>&#x2248;</mo><mn>0</mn><mo>,</mo><mn>196</mn><mo stretchy="false">(</mo><mi>m</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>s</mi><mo stretchy="false">)</mo></math>" id="MathJax-Element-4-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-31" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-32" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-33" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-34" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-35" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-36" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-37" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-38" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-39" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 1.399em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.47em; width: 1.978em;"><span class="mjx-texatom" id="MJXc-Node-40" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-41" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-42" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">0</span></span><span class="mjx-mo" id="MJXc-Node-43" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn" id="MJXc-Node-44" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">2</span></span></span></span></span><span class="mjx-denominator" style="bottom: -0.763em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 1.978em;"><span class="mjx-texatom" id="MJXc-Node-45" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-46" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-47" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span><span class="mjx-mo" id="MJXc-Node-48" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn" id="MJXc-Node-49" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">02</span></span></span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 1.399em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.579em; margin: 0px; padding: 0px; vertical-align: -0.54em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-50" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.186em 0px 0.324em; white-space: pre;">≈</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-51" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">0</span></span><span class="mjx-mo" id="MJXc-Node-52" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn MJXc-space1" id="MJXc-Node-53" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.167em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">196</span></span><span class="mjx-mo" id="MJXc-Node-54" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">(</span></span><span class="mjx-mi" id="MJXc-Node-55" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">m</span></span><span class="mjx-texatom" id="MJXc-Node-56" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-57" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mo" id="MJXc-Node-58" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">/</span></span></span></span><span class="mjx-mi" id="MJXc-Node-59" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span><span class="mjx-mo" id="MJXc-Node-60" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">)</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>0</mn><mo>,</mo><mn>2</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>1</mn><mo>,</mo><mn>02</mn></mrow></mfrac><mo>≈</mo><mn>0</mn><mo>,</mo><mn>196</mn><mo stretchy="false">(</mo><mi>�</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>�</mi><mo stretchy="false">)</mo></math></span></span></p></div><div class="box-question top20" id="sub-question-4" style="background-color: white; border-bottom: 1px dotted rgb(225, 225, 225); font-family: OpenSans, Tahoma, Helvetica, sans-serif; font-size: 18px; height: auto; line-height: 26px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 20px !important; padding: 0px; text-align: justify; width: calc(100% - 40px) !important;"><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="color: #2888e1; font-family: OpenSansBold; margin: 0px; padding: 0px;">10.4</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Xác định tốc độ của một người chạy cự li 100 m được mô tả trong hình dưới đây.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">                       <img src="https://img.loigiaihay.com/picture/2022/0808/13.png" style="height: auto; margin: 0px; max-height: 100%; max-width: 100%; padding: 0px;" /></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Phương pháp giải:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Biểu thức tính tốc độ: <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac></math>" id="MathJax-Element-5-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-61" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-62" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-63" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-64" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-65" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-66" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-67" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) v: tốc độ chuyển động của vật (m/s)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) s: quãng đường đi được của vật (m)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) t: thời gian đi được quãng đường s của vật (s)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Lời giải chi tiết:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Tóm tắt:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">s = 100 m</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">t =  22 s</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">v = ?</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Lời giải:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Tốc độ của người chạy cự li 100 m được mô tả trong hình là:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>100</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>22</mn></mrow></mfrac><mo>&#x2248;</mo><mn>4</mn><mo>,</mo><mn>55</mn><mo stretchy="false">(</mo><mi>m</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>s</mi><mo stretchy="false">)</mo></math>" id="MathJax-Element-6-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-68" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-69" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-70" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-71" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-72" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-73" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-74" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-75" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-76" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 1.202em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.298em; width: 1.7em;"><span class="mjx-texatom" id="MJXc-Node-77" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-78" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-79" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">100</span></span></span></span></span><span class="mjx-denominator" style="bottom: -0.569em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 1.7em;"><span class="mjx-texatom" id="MJXc-Node-80" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-81" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-82" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">22</span></span></span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 1.202em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.32em; margin: 0px; padding: 0px; vertical-align: -0.402em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-83" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.186em 0px 0.324em; white-space: pre;">≈</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-84" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">4</span></span><span class="mjx-mo" id="MJXc-Node-85" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn MJXc-space1" id="MJXc-Node-86" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.167em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">55</span></span><span class="mjx-mo" id="MJXc-Node-87" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">(</span></span><span class="mjx-mi" id="MJXc-Node-88" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">m</span></span><span class="mjx-texatom" id="MJXc-Node-89" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-90" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mo" id="MJXc-Node-91" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">/</span></span></span></span><span class="mjx-mi" id="MJXc-Node-92" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span><span class="mjx-mo" id="MJXc-Node-93" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">)</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>100</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>22</mn></mrow></mfrac><mo>≈</mo><mn>4</mn><mo>,</mo><mn>55</mn><mo stretchy="false">(</mo><mi>�</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>�</mi><mo stretchy="false">)</mo></math></span></span></p></div><div class="box-question top20" id="sub-question-5" style="background-color: white; border-bottom: 1px dotted rgb(225, 225, 225); font-family: OpenSans, Tahoma, Helvetica, sans-serif; font-size: 18px; height: auto; line-height: 26px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 20px !important; padding: 0px; text-align: justify; width: calc(100% - 40px) !important;"><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="color: #2888e1; font-family: OpenSansBold; margin: 0px; padding: 0px;">10.5</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">a) Để xác định tốc độ của một vật đang chuyển động, ta cần biết những thông tin gì?</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">b) Lập kế hoạch và tiến hành đo tốc độ chuyển động của một xe đồ chơi chạy pin. Yêu cầu nêu rõ: dụng cụ đo, cách tiến hành và báo cáo kết quả.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Phương pháp giải:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Để đo tốc độ, người ta cần đo quãng đường s vật đi được và thời gian chuyển động t của vật.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Lời giải chi tiết:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">a) Để xác định tốc độ của một vật đang chuyển động, ta cần biết quãng đường s vật đi được và thời gian chuyển động t của vật.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">b) Lập kế hoạch và tiến hành đo tốc độ chuyển động của một xe đồ chơi chạy pin.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">- Dụng cụ: tấm ván phẳng (hoặc mặt đất phẳng), thước, bút đánh dấu, đồng hồ bấm giây, xe đồ chơi chạy bằng pin.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">- Cách tiến hành:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+ Dùng bút đánh dấu vạch xuất phát và vạch đích. Dùng thước đo độ dài quãng đường s vật đi được bằng cách đo khoảng cách giữa vạch xuất phát và vạch đích.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+ Giữ xe tại vạch xuất phát rồi bấm nút khởi động. Dùng đồng hồ bấm giây để đo thời gian t từ lúc xe bắt đầu xuất phát đến lúc xe chạm vạch đích.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+ Thực hiện ba lần đo, lấy giá trị trung bình của các phép đo.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">- Báo cáo kết quả đo vào bảng sau:</p><table border="1" cellpadding="0" cellspacing="0" style="border-spacing: 0px; margin: 0px 0px 1.4em; padding: 0px; vertical-align: middle; width: 585px;"><tbody style="margin: 0px; padding: 0px;"><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Lần đo</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Quãng đường(m)</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Thời gian(s)</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">1</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>s</mi><mn>1</mn></msub></mrow></math>" id="MathJax-Element-7-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-94" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-95" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-96" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-97" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-98" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-99" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-100" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span></span></span></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>1</mn></msub></mrow></math></span></span>=</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>t</mi><mn>1</mn></msub></mrow></math>" id="MathJax-Element-8-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-101" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-102" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-103" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-104" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-105" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-106" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-107" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span></span></span></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>1</mn></msub></mrow></math></span></span>=</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">2</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>s</mi><mn>2</mn></msub></mrow></math>" id="MathJax-Element-9-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-108" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-109" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-110" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-111" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-112" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-113" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-114" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">2</span></span></span></span></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>2</mn></msub></mrow></math></span></span>=</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>t</mi><mn>2</mn></msub></mrow></math>" id="MathJax-Element-10-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-115" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-116" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-117" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-118" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-119" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-120" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-121" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">2</span></span></span></span></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>2</mn></msub></mrow></math></span></span>=</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">3</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>s</mi><mn>3</mn></msub></mrow></math>" id="MathJax-Element-11-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-122" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-123" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-124" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-125" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-126" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-127" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-128" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">3</span></span></span></span></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>3</mn></msub></mrow></math></span></span>=</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>t</mi><mn>3</mn></msub></mrow></math>" id="MathJax-Element-12-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-129" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-130" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-131" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-132" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-133" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-134" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-135" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">3</span></span></span></span></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>3</mn></msub></mrow></math></span></span>=</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Giá trị trung bình</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>s</mi><mrow class="MJX-TeXAtom-ORD"><mi>t</mi><mi>b</mi></mrow></msub></mrow><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mrow class="MJX-TeXAtom-ORD"><msub><mi>s</mi><mn>1</mn></msub></mrow><mo>+</mo><mrow class="MJX-TeXAtom-ORD"><msub><mi>s</mi><mn>2</mn></msub></mrow><mo>+</mo><mrow class="MJX-TeXAtom-ORD"><msub><mi>s</mi><mn>3</mn></msub></mrow></mrow><mn>3</mn></mfrac></math>" id="MathJax-Element-13-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-136" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-137" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-138" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-139" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-140" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-141" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.219em;"><span class="mjx-texatom" id="MJXc-Node-142" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-143" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-144" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span><span class="mjx-mi" id="MJXc-Node-145" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.461em 0px 0.278em; white-space: pre;">b</span></span></span></span></span></span></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-146" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-147" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 3.062em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.351em; width: 4.33em;"><span class="mjx-texatom" id="MJXc-Node-148" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-149" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-150" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-151" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-152" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-153" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 10.8867px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-154" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span></span></span></span></span><span class="mjx-mo" id="MJXc-Node-155" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.278em 0px 0.416em; white-space: pre;">+</span></span><span class="mjx-texatom" id="MJXc-Node-156" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-157" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-158" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-159" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 10.8867px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-160" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">2</span></span></span></span></span></span><span class="mjx-mo" id="MJXc-Node-161" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.278em 0px 0.416em; white-space: pre;">+</span></span><span class="mjx-texatom" id="MJXc-Node-162" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-163" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-164" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-165" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 10.8867px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-166" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">3</span></span></span></span></span></span></span></span></span><span class="mjx-denominator" style="bottom: -0.59em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 4.33em;"><span class="mjx-mn" id="MJXc-Node-167" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">3</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 3.062em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.373em; margin: 0px; padding: 0px; vertical-align: -0.417em; width: 0px;"></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mrow class="MJX-TeXAtom-ORD"><mi>�</mi><mi>�</mi></mrow></msub></mrow><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>1</mn></msub></mrow><mo>+</mo><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>2</mn></msub></mrow><mo>+</mo><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>3</mn></msub></mrow></mrow><mn>3</mn></mfrac></math></span></span></p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>t</mi><mrow class="MJX-TeXAtom-ORD"><mi>t</mi><mi>b</mi></mrow></msub></mrow><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mrow class="MJX-TeXAtom-ORD"><msub><mi>t</mi><mn>1</mn></msub></mrow><mo>+</mo><mrow class="MJX-TeXAtom-ORD"><msub><mi>t</mi><mn>2</mn></msub></mrow><mo>+</mo><mrow class="MJX-TeXAtom-ORD"><msub><mi>t</mi><mn>3</mn></msub></mrow></mrow><mn>3</mn></mfrac></math>" id="MathJax-Element-14-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-168" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-169" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-170" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-171" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-172" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-173" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.219em;"><span class="mjx-texatom" id="MJXc-Node-174" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-175" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-176" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span><span class="mjx-mi" id="MJXc-Node-177" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.461em 0px 0.278em; white-space: pre;">b</span></span></span></span></span></span></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-178" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-179" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 2.832em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.394em; width: 4.006em;"><span class="mjx-texatom" id="MJXc-Node-180" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-181" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-182" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-183" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-184" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-185" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 10.8867px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-186" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span></span></span></span></span><span class="mjx-mo" id="MJXc-Node-187" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.278em 0px 0.416em; white-space: pre;">+</span></span><span class="mjx-texatom" id="MJXc-Node-188" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-189" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-190" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-191" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 10.8867px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-192" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">2</span></span></span></span></span></span><span class="mjx-mo" id="MJXc-Node-193" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.278em 0px 0.416em; white-space: pre;">+</span></span><span class="mjx-texatom" id="MJXc-Node-194" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-195" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-196" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-197" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 10.8867px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-198" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">3</span></span></span></span></span></span></span></span></span><span class="mjx-denominator" style="bottom: -0.59em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 4.006em;"><span class="mjx-mn" id="MJXc-Node-199" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">3</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 2.832em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.403em; margin: 0px; padding: 0px; vertical-align: -0.417em; width: 0px;"></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mrow class="MJX-TeXAtom-ORD"><mi>�</mi><mi>�</mi></mrow></msub></mrow><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>1</mn></msub></mrow><mo>+</mo><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>2</mn></msub></mrow><mo>+</mo><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>3</mn></msub></mrow></mrow><mn>3</mn></mfrac></math></span></span></p></td></tr></tbody></table><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+ Dùng công thức <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mrow class="MJX-TeXAtom-ORD"><msub><mi>s</mi><mrow class="MJX-TeXAtom-ORD"><mi>t</mi><mi>b</mi></mrow></msub></mrow></mrow><mrow class="MJX-TeXAtom-ORD"><mrow class="MJX-TeXAtom-ORD"><msub><mi>t</mi><mrow class="MJX-TeXAtom-ORD"><mi>t</mi><mi>b</mi></mrow></msub></mrow></mrow></mfrac></math>" id="MathJax-Element-15-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-200" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-201" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-202" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-203" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-204" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-205" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-206" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-207" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-208" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.893em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.207em; width: 1.263em;"><span class="mjx-texatom" id="MJXc-Node-209" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-210" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-211" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-212" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-213" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-214" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 10.8867px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.219em;"><span class="mjx-texatom" id="MJXc-Node-215" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-216" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-217" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span><span class="mjx-mi" id="MJXc-Node-218" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.461em 0px 0.278em; white-space: pre;">b</span></span></span></span></span></span></span></span></span></span></span><span class="mjx-denominator" style="bottom: -0.684em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 1.263em;"><span class="mjx-texatom" id="MJXc-Node-219" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-220" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-221" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-222" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-223" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-224" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 10.8867px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.219em;"><span class="mjx-texatom" id="MJXc-Node-225" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-226" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-227" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span><span class="mjx-mi" id="MJXc-Node-228" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.461em 0px 0.278em; white-space: pre;">b</span></span></span></span></span></span></span></span></span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.893em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.338em; margin: 0px; padding: 0px; vertical-align: -0.484em; width: 0px;"></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mrow class="MJX-TeXAtom-ORD"><mi>�</mi><mi>�</mi></mrow></msub></mrow></mrow><mrow class="MJX-TeXAtom-ORD"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mrow class="MJX-TeXAtom-ORD"><mi>�</mi><mi>�</mi></mrow></msub></mrow></mrow></mfrac></math></span></span></p></div><p><span style="background-color: white; font-family: OpenSans, Tahoma, Helvetica, sans-serif; font-size: 18px; text-align: justify;"> </span><span style="background-color: white; font-family: OpenSans, Tahoma, Helvetica, sans-serif; font-size: 18px; text-align: justify;">để tính tốc độ của xe đồ chơi chạy bằng pin.</span></p><div class="box-question top20" id="sub-question-6" style="background-color: white; border-bottom: 1px dotted rgb(225, 225, 225); font-family: OpenSans, Tahoma, Helvetica, sans-serif; font-size: 18px; height: auto; line-height: 26px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 20px !important; padding: 0px; text-align: justify; width: calc(100% - 40px) !important;"><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="color: #2888e1; font-family: OpenSansBold; margin: 0px; padding: 0px;">10.6</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Hình dưới đây mô tả một cách đo tốc độ chảy của dòng nước bằng vật nổi.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">a) Em cần những dụng cụ nào để thực hiện phép đo này?</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">b) Mô tả cách đo tốc độ chảy của dòng nước.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; text-align: center; word-break: normal;"><img src="https://img.loigiaihay.com/picture/2022/0808/14.png" style="height: auto; margin: 0px; max-height: 100%; max-width: 100%; padding: 0px;" /></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Phương pháp giải:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Để đo tốc độ, người ta cần đo quãng đường s vật đi được và thời gian chuyển động t của vật.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Lời giải chi tiết:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">a) Để đo tốc độ chảy của dòng nước bằng vật nổi, ta cần: thước dây, hồ bấm giây, vật nổi, dây căng và vật cắm mốc.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">b) Cách đo tốc độ chảy của dòng nước:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">- Cắm mốc căng dây để đánh dấu vạch xuất phát và vạch đích.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">- Dùng thước dây đo độ dài quãng đường s vật đi được bằng cách đo khoảng cách giữa vạch xuất phát và vạch đích.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">- Bạn A thả vật nổi và ra tín hiệu để bạn B bấm đồng hồ bắt đầu đo. Bạn B quan sát vật nổi chạm vạch đích thì bấm đồng hồ dừng đo và đọc kết quả đo thời gian t.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">- Tính tốc độ chảy của dòng nước bằng công thức: <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac></math>" id="MathJax-Element-16-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-229" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-230" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-231" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-232" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-233" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-234" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-235" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac></math></span></span></p></div><div class="box-question top20" id="sub-question-7" style="background-color: white; border-bottom: 1px dotted rgb(225, 225, 225); font-family: OpenSans, Tahoma, Helvetica, sans-serif; font-size: 18px; height: auto; line-height: 26px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 20px !important; padding: 0px; text-align: justify; width: calc(100% - 40px) !important;"><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="color: #2888e1; font-family: OpenSansBold; margin: 0px; padding: 0px;">10.7</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Bảng dưới đây cho biết thông tin về thành tích bơi ở cự li 50 m của một số nữ vận động viên quốc tế.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><em style="margin: 0px; padding: 0px;">(Nguồn: </em><a href="http://www.fina.org/" style="color: #336699; margin: 0px; outline: 0px; padding: 0px; text-decoration-line: none;"><em style="margin: 0px; padding: 0px;">http://www.fina.org</em></a><em style="margin: 0px; padding: 0px;">)</em></p><div align="center" style="line-height: 26px; margin: 0px; padding: 0px;"><table border="1" cellpadding="0" cellspacing="0" style="border-spacing: 0px; margin: 0px 0px 1.4em; padding: 0px; vertical-align: middle; width: 585px;"><tbody style="margin: 0px; padding: 0px;"><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Nội dung bơi</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Thời gian bơi (s)</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="113"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Tên vận động viên</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Quốc tịch</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="151"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Sự kiện</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Tốc độ bơi (m/s)</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">50 m bơi tự do</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">22,93</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="113"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Ramoni Kromowidjojo</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Hà Lan</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="151"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><em style="margin: 0px; padding: 0px;">World Cup 2017</em></p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">?</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">50 m bơi ngửa</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">25,27</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="113"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Margaret Mc Neil</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Canada</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="151"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><em style="margin: 0px; padding: 0px;">Final World Swimming Championship 2021</em></p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">?</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">50 m bơi bướm</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">24,38</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="113"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Therese Alshammar</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Thụy Điển</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="151"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><em style="margin: 0px; padding: 0px;">World Cup 2009</em></p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">?</p></td></tr></tbody></table></div><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">a) Tính tốc độ bơi của các vận động viên.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">b) Để đo tốc độ bơi của một người, em cần những dụng cụ gì?</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Phương pháp giải:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Biểu thức tính tốc độ: <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac></math>" id="MathJax-Element-17-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-236" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-237" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-238" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-239" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-240" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-241" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-242" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) v: tốc độ chuyển động của vật (m/s)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) s: quãng đường đi được của vật (m)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) t: thời gian đi được quãng đường s của vật (s)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Lời giải chi tiết:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Tóm tắt:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>s</mi><mn>1</mn></msub></mrow><mo>=</mo><mrow class="MJX-TeXAtom-ORD"><msub><mi>s</mi><mn>2</mn></msub></mrow><mo>=</mo><mrow class="MJX-TeXAtom-ORD"><msub><mi>s</mi><mn>3</mn></msub></mrow><mo>=</mo><mn>50</mn></math>" id="MathJax-Element-18-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-243" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-244" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-245" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-246" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-247" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-248" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-249" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span></span></span></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-250" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-texatom MJXc-space3" id="MJXc-Node-251" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-252" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-253" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-254" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-255" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">2</span></span></span></span></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-256" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-texatom MJXc-space3" id="MJXc-Node-257" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-258" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-259" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-260" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-261" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">3</span></span></span></span></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-262" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-263" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">50</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>1</mn></msub></mrow><mo>=</mo><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>2</mn></msub></mrow><mo>=</mo><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>3</mn></msub></mrow><mo>=</mo><mn>50</mn></math></span></span>m</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>t</mi><mn>1</mn></msub></mrow><mo>=</mo><mn>22</mn><mo>,</mo><mn>93</mn></math>" id="MathJax-Element-19-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-264" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-265" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-266" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-267" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-268" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-269" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-270" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span></span></span></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-271" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-272" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">22</span></span><span class="mjx-mo" id="MJXc-Node-273" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn MJXc-space1" id="MJXc-Node-274" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.167em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">93</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>1</mn></msub></mrow><mo>=</mo><mn>22</mn><mo>,</mo><mn>93</mn></math></span></span>s, <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>v</mi><mn>1</mn></msub></mrow></math>" id="MathJax-Element-20-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-275" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-276" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-277" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-278" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-279" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-280" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-281" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span></span></span></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>1</mn></msub></mrow></math></span></span>=?</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>t</mi><mn>2</mn></msub></mrow><mo>=</mo><mn>25</mn><mo>,</mo><mn>27</mn></math>" id="MathJax-Element-21-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-282" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-283" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-284" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-285" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-286" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-287" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-288" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">2</span></span></span></span></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-289" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-290" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">25</span></span><span class="mjx-mo" id="MJXc-Node-291" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn MJXc-space1" id="MJXc-Node-292" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.167em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">27</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>2</mn></msub></mrow><mo>=</mo><mn>25</mn><mo>,</mo><mn>27</mn></math></span></span>s, <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>v</mi><mn>2</mn></msub></mrow></math>" id="MathJax-Element-22-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-293" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-294" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-295" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-296" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-297" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-298" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-299" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">2</span></span></span></span></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>2</mn></msub></mrow></math></span></span>=?</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>t</mi><mn>3</mn></msub></mrow><mo>=</mo><mn>24</mn><mo>,</mo><mn>38</mn></math>" id="MathJax-Element-23-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-300" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-301" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-302" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-303" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-304" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-305" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-306" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">3</span></span></span></span></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-307" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-308" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">24</span></span><span class="mjx-mo" id="MJXc-Node-309" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn MJXc-space1" id="MJXc-Node-310" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.167em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">38</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>3</mn></msub></mrow><mo>=</mo><mn>24</mn><mo>,</mo><mn>38</mn></math></span></span>s, <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>v</mi><mn>3</mn></msub></mrow></math>" id="MathJax-Element-24-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-311" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-312" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-texatom" id="MJXc-Node-313" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-314" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-msubsup" id="MJXc-Node-315" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-base" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-316" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span></span><span class="mjx-sub" style="box-sizing: content-box !important; display: inline-block; font-size: 15.3985px; margin: 0px; padding: 0px 0.071em 0px 0px; vertical-align: -0.212em;"><span class="mjx-mn" id="MJXc-Node-317" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">3</span></span></span></span></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mrow class="MJX-TeXAtom-ORD"><msub><mi>�</mi><mn>3</mn></msub></mrow></math></span></span>=?</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Lời giải:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">a) Tốc độ bơi của vận động viên người Hà Lan là:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac><mo stretchy="false">&#x21D2;</mo><mi>v</mi><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>50</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>22</mn><mo>,</mo><mn>93</mn></mrow></mfrac><mo>&#x2248;</mo><mn>2</mn><mo>,</mo><mn>18</mn><mo stretchy="false">(</mo><mi>m</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>s</mi><mo stretchy="false">)</mo></math>" id="MathJax-Element-25-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-318" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-319" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-320" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-321" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-322" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-323" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-324" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-325" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.232em 0px 0.37em; white-space: pre;">⇒</span></span><span class="mjx-mi MJXc-space3" id="MJXc-Node-326" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-327" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-328" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 1.752em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.298em; width: 2.478em;"><span class="mjx-texatom" id="MJXc-Node-329" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-330" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-331" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">50</span></span></span></span></span><span class="mjx-denominator" style="bottom: -0.763em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 2.478em;"><span class="mjx-texatom" id="MJXc-Node-332" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-333" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-334" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">22</span></span><span class="mjx-mo" id="MJXc-Node-335" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn" id="MJXc-Node-336" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">93</span></span></span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 1.752em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.457em; margin: 0px; padding: 0px; vertical-align: -0.54em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-337" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.186em 0px 0.324em; white-space: pre;">≈</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-338" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">2</span></span><span class="mjx-mo" id="MJXc-Node-339" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn MJXc-space1" id="MJXc-Node-340" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.167em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">18</span></span><span class="mjx-mo" id="MJXc-Node-341" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">(</span></span><span class="mjx-mi" id="MJXc-Node-342" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">m</span></span><span class="mjx-texatom" id="MJXc-Node-343" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-344" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mo" id="MJXc-Node-345" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">/</span></span></span></span><span class="mjx-mi" id="MJXc-Node-346" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span><span class="mjx-mo" id="MJXc-Node-347" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">)</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac><mo stretchy="false">⇒</mo><mi>�</mi><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>50</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>22</mn><mo>,</mo><mn>93</mn></mrow></mfrac><mo>≈</mo><mn>2</mn><mo>,</mo><mn>18</mn><mo stretchy="false">(</mo><mi>�</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>�</mi><mo stretchy="false">)</mo></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Tốc độ bơi của vận động viên người Canada là:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac><mo stretchy="false">&#x21D2;</mo><mi>v</mi><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>50</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>25</mn><mo>,</mo><mn>27</mn></mrow></mfrac><mo>&#x2248;</mo><mn>1</mn><mo>,</mo><mn>98</mn><mo stretchy="false">(</mo><mi>m</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>s</mi><mo stretchy="false">)</mo></math>" id="MathJax-Element-26-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-348" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-349" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-350" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-351" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-352" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-353" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-354" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-355" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.232em 0px 0.37em; white-space: pre;">⇒</span></span><span class="mjx-mi MJXc-space3" id="MJXc-Node-356" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-357" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-358" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 1.752em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.298em; width: 2.478em;"><span class="mjx-texatom" id="MJXc-Node-359" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-360" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-361" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">50</span></span></span></span></span><span class="mjx-denominator" style="bottom: -0.773em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 2.478em;"><span class="mjx-texatom" id="MJXc-Node-362" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-363" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-364" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">25</span></span><span class="mjx-mo" id="MJXc-Node-365" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn" id="MJXc-Node-366" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">27</span></span></span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 1.752em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.465em; margin: 0px; padding: 0px; vertical-align: -0.547em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-367" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.186em 0px 0.324em; white-space: pre;">≈</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-368" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span><span class="mjx-mo" id="MJXc-Node-369" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn MJXc-space1" id="MJXc-Node-370" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.167em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">98</span></span><span class="mjx-mo" id="MJXc-Node-371" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">(</span></span><span class="mjx-mi" id="MJXc-Node-372" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">m</span></span><span class="mjx-texatom" id="MJXc-Node-373" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-374" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mo" id="MJXc-Node-375" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">/</span></span></span></span><span class="mjx-mi" id="MJXc-Node-376" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span><span class="mjx-mo" id="MJXc-Node-377" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">)</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac><mo stretchy="false">⇒</mo><mi>�</mi><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>50</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>25</mn><mo>,</mo><mn>27</mn></mrow></mfrac><mo>≈</mo><mn>1</mn><mo>,</mo><mn>98</mn><mo stretchy="false">(</mo><mi>�</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>�</mi><mo stretchy="false">)</mo></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Tốc độ bơi của vận động viên người Thụy Điển là:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac><mo stretchy="false">&#x21D2;</mo><mi>v</mi><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>50</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>24</mn><mo>,</mo><mn>38</mn></mrow></mfrac><mo>&#x2248;</mo><mn>2</mn><mo>,</mo><mn>05</mn><mo stretchy="false">(</mo><mi>m</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>s</mi><mo stretchy="false">)</mo></math>" id="MathJax-Element-27-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-378" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-379" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-380" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-381" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-382" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-383" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-384" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-385" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.232em 0px 0.37em; white-space: pre;">⇒</span></span><span class="mjx-mi MJXc-space3" id="MJXc-Node-386" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-387" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-388" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 1.752em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.298em; width: 2.478em;"><span class="mjx-texatom" id="MJXc-Node-389" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-390" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-391" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">50</span></span></span></span></span><span class="mjx-denominator" style="bottom: -0.774em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 2.478em;"><span class="mjx-texatom" id="MJXc-Node-392" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-393" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-394" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">24</span></span><span class="mjx-mo" id="MJXc-Node-395" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn" id="MJXc-Node-396" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">38</span></span></span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 1.752em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.465em; margin: 0px; padding: 0px; vertical-align: -0.547em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-397" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.186em 0px 0.324em; white-space: pre;">≈</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-398" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">2</span></span><span class="mjx-mo" id="MJXc-Node-399" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn MJXc-space1" id="MJXc-Node-400" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.167em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">05</span></span><span class="mjx-mo" id="MJXc-Node-401" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">(</span></span><span class="mjx-mi" id="MJXc-Node-402" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">m</span></span><span class="mjx-texatom" id="MJXc-Node-403" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-404" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mo" id="MJXc-Node-405" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">/</span></span></span></span><span class="mjx-mi" id="MJXc-Node-406" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span><span class="mjx-mo" id="MJXc-Node-407" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">)</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac><mo stretchy="false">⇒</mo><mi>�</mi><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>50</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>24</mn><mo>,</mo><mn>38</mn></mrow></mfrac><mo>≈</mo><mn>2</mn><mo>,</mo><mn>05</mn><mo stretchy="false">(</mo><mi>�</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>�</mi><mo stretchy="false">)</mo></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">b) Để đo tốc độ bơi của một người, em cần những dụng cụ là: Thước dây, đồng hồ bấm giây.</p></div><div class="box-question top20" id="sub-question-8" style="background-color: white; border-bottom: 1px dotted rgb(225, 225, 225); font-family: OpenSans, Tahoma, Helvetica, sans-serif; font-size: 18px; height: auto; line-height: 26px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 20px !important; padding: 0px; text-align: justify; width: calc(100% - 40px) !important;"><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="color: #2888e1; font-family: OpenSansBold; margin: 0px; padding: 0px;">10.8</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Hình dưới đây mô tả một cách đo tốc độ lan truyền âm thanh trong không khí, bằng cách tạo ra tiếng thước gõ lên mặt bàn. Hai micro được kết nối với bộ đếm thời gian. Các cảm biến gắn trong bộ đếm thời gian thu nhận tín hiệu âm thanh đến mỗi micro và hiển thị trên màn hình khoảng thời gian từ lúc micro 1 nhận tín hiệu đến lúc micro 2 nhận tín hiệu.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; text-align: center; word-break: normal;"><img src="https://img.loigiaihay.com/picture/2022/0808/15.png" style="height: auto; margin: 0px; max-height: 100%; max-width: 100%; padding: 0px;" /></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Hãy trình bày cách tính tốc độ lan truyền âm thanh trong không khí.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">b) Giả sử trong một lần đo, người ta bố trí khoảng cách giữa hai micro là 1,2 m và khoảng thời gian hiển thị trên màn hình của bộ đếm thời gian là 0,0035 s. Tính tốc độ lan truyền âm thanh trong không khí.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Phương pháp giải:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Biểu thức tính tốc độ: <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac></math>" id="MathJax-Element-28-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-408" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-409" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-410" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-411" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-412" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-413" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-414" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) v: tốc độ chuyển động của vật (m/s)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) s: quãng đường đi được của vật (m)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) t: thời gian đi được quãng đường s của vật (s)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Lời giải chi tiết:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Tóm tắt:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">s = 1,2 m</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">t = 0,0035 s</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">v=?</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Lời giải:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">a) Cách tính tốc độ truyền âm thanh:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">- Đo khoảng cách s giữa hai micro.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">- Đọc giá trị thời gian t hiển thị trên màn hình bộ đếm thời gian.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">- Tính tốc độ theo công thức: <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac></math>" id="MathJax-Element-29-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-415" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-416" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-417" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-418" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-419" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-420" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-421" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">b) Tốc độ lan truyền âm thanh trong không khí:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac><mo stretchy="false">&#x21D2;</mo><mi>v</mi><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>1</mn><mo>,</mo><mn>2</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>0</mn><mo>,</mo><mn>0035</mn></mrow></mfrac><mo>&#x2248;</mo><mn>342</mn><mo>,</mo><mn>86</mn><mo stretchy="false">(</mo><mi>m</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>s</mi><mo stretchy="false">)</mo></math>" id="MathJax-Element-30-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-422" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-423" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-424" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-425" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-426" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-427" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-428" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-429" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.232em 0px 0.37em; white-space: pre;">⇒</span></span><span class="mjx-mi MJXc-space3" id="MJXc-Node-430" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-431" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-432" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 2.106em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.47em; width: 2.978em;"><span class="mjx-texatom" id="MJXc-Node-433" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-434" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-435" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span><span class="mjx-mo" id="MJXc-Node-436" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn" id="MJXc-Node-437" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">2</span></span></span></span></span><span class="mjx-denominator" style="bottom: -0.763em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 2.978em;"><span class="mjx-texatom" id="MJXc-Node-438" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-439" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-440" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">0</span></span><span class="mjx-mo" id="MJXc-Node-441" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn" id="MJXc-Node-442" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">0035</span></span></span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 2.106em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.579em; margin: 0px; padding: 0px; vertical-align: -0.54em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-443" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.186em 0px 0.324em; white-space: pre;">≈</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-444" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">342</span></span><span class="mjx-mo" id="MJXc-Node-445" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn MJXc-space1" id="MJXc-Node-446" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.167em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">86</span></span><span class="mjx-mo" id="MJXc-Node-447" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">(</span></span><span class="mjx-mi" id="MJXc-Node-448" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">m</span></span><span class="mjx-texatom" id="MJXc-Node-449" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-450" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mo" id="MJXc-Node-451" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">/</span></span></span></span><span class="mjx-mi" id="MJXc-Node-452" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span><span class="mjx-mo" id="MJXc-Node-453" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">)</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac><mo stretchy="false">⇒</mo><mi>�</mi><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>1</mn><mo>,</mo><mn>2</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>0</mn><mo>,</mo><mn>0035</mn></mrow></mfrac><mo>≈</mo><mn>342</mn><mo>,</mo><mn>86</mn><mo stretchy="false">(</mo><mi>�</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>�</mi><mo stretchy="false">)</mo></math></span></span></p></div><div class="box-question top20" id="sub-question-9" style="background-color: white; border-bottom: 1px dotted rgb(225, 225, 225); font-family: OpenSans, Tahoma, Helvetica, sans-serif; font-size: 18px; height: auto; line-height: 26px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 20px !important; padding: 0px; text-align: justify; width: calc(100% - 40px) !important;"><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="color: #2888e1; font-family: OpenSansBold; margin: 0px; padding: 0px;">10.9</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Để đo tốc độ gió, người ta chỉ cần một chong chóng gió và một đồng hồ bấm giây. Bằng cách đo số vòng quay của chong chóng trong một khoảng thời gian nhất định, người ta có thể tính ra tốc độ gió.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">                       <img src="https://img.loigiaihay.com/picture/2022/0808/16.png" style="height: auto; margin: 0px; max-height: 100%; max-width: 100%; padding: 0px;" /></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">a) Hãy trình bày cách tính tốc độ gió.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">b) Trong một lần đo với chong chóng gió có bán kính 60 cm, người ta đếm được chong chóng quay 20 vòng trong thời gian 4,2 s. Tính tốc độ gió.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Phương pháp giải:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Biểu thức tính tốc độ: <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac></math>" id="MathJax-Element-31-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-454" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-455" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-456" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-457" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-458" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-459" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-460" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) v: tốc độ chuyển động của vật (m/s)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) s: quãng đường đi được của vật (m)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) t: thời gian đi được quãng đường s của vật (s)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Đổi đơn vị độ dài: 1 cm =<span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>1</mn><mrow class="MJX-TeXAtom-ORD"><mn>100</mn></mrow></mfrac><mi>m</mi></math>" id="MathJax-Element-32-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-461" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-462" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mfrac" id="MJXc-Node-463" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 1.202em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.276em; width: 1.7em;"><span class="mjx-mn" id="MJXc-Node-464" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span></span><span class="mjx-denominator" style="bottom: -0.591em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 1.7em;"><span class="mjx-texatom" id="MJXc-Node-465" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-466" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-467" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">100</span></span></span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 1.202em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.32em; margin: 0px; padding: 0px; vertical-align: -0.418em; width: 0px;"></span></span><span class="mjx-mi" id="MJXc-Node-468" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">m</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>1</mn><mrow class="MJX-TeXAtom-ORD"><mn>100</mn></mrow></mfrac><mi>�</mi></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Lời giải chi tiết:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Tóm tắt:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">R = 60 cm = 0,6 m</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">n = 20 vòng</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">t = 4,2 s</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">v=?</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Lời giải:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Quãng đường tại 1 điểm trên 1 cánh chong chóng khi quay được 1 vòng ( tương đương chu vi chong chóng) là:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">            0,6.3,14=1,884(m)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Quãng đường mà điểm đó đi được trong 20 vòng là:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">            1,884.20=37,68(m)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Tốc độ gió là:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>37</mn><mo>,</mo><mn>68</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>4</mn><mo>,</mo><mn>2</mn></mrow></mfrac><mo>&#x2248;</mo><mn>8</mn><mo>,</mo><mn>97</mn></math>" id="MathJax-Element-33-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-469" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-470" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-471" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-472" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-473" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-474" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-475" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-476" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-477" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 1.752em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.48em; width: 2.478em;"><span class="mjx-texatom" id="MJXc-Node-478" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-479" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-480" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">37</span></span><span class="mjx-mo" id="MJXc-Node-481" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn" id="MJXc-Node-482" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">68</span></span></span></span></span><span class="mjx-denominator" style="bottom: -0.774em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 2.478em;"><span class="mjx-texatom" id="MJXc-Node-483" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-484" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-485" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">4</span></span><span class="mjx-mo" id="MJXc-Node-486" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn" id="MJXc-Node-487" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">2</span></span></span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 1.752em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.594em; margin: 0px; padding: 0px; vertical-align: -0.547em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-488" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.186em 0px 0.324em; white-space: pre;">≈</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-489" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">8</span></span><span class="mjx-mo" id="MJXc-Node-490" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn MJXc-space1" id="MJXc-Node-491" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.167em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">97</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>37</mn><mo>,</mo><mn>68</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>4</mn><mo>,</mo><mn>2</mn></mrow></mfrac><mo>≈</mo><mn>8</mn><mo>,</mo><mn>97</mn></math></span></span>(m/s)</p></div><div class="box-question top20" id="sub-question-10" style="background-color: white; border-bottom: 1px dotted rgb(225, 225, 225); font-family: OpenSans, Tahoma, Helvetica, sans-serif; font-size: 18px; height: auto; line-height: 26px; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 20px !important; padding: 0px; text-align: justify; width: calc(100% - 40px) !important;"><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="color: #2888e1; font-family: OpenSansBold; margin: 0px; padding: 0px;">10.10</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Bảng dưới đây cho biết số chỉ của đồng hồ đo quãng đường trên một xe máy tại các thời điểm khác nhau kể từ lúc xuất phát ( 6 giờ 30 phút ).</p><table border="1" cellpadding="0" cellspacing="0" style="border-spacing: 0px; margin: 0px 0px 1.4em; padding: 0px; vertical-align: middle; width: 585px;"><tbody style="margin: 0px; padding: 0px;"><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Thời điểm</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Số chỉ của đồng hồ đo quãng đường (km)</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Quãng đường đi được tính từ lúc xuất phát (km)</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">6 giờ 30 phút</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">10200</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">0</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">7 giờ</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">10220</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">?</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">7 giờ 30 phút</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">10240</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">?</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">8 giờ</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">10260</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">?</p></td></tr></tbody></table><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">a) Xác định quãng đường xe đi được tính từ lúc xuất phát cho đến các thời điểm đã cho và điền vào bảng.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">b) Tính tốc độ của xe trong các khoảng thời gian sau:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">    - Từ lúc 6 giờ 30 phút đến 7 giờ.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">    - Từ lúc 6 giờ 30 phút đến 7 giờ 30 phút.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">    - Từ lúc 6 giờ 30 phút đến 8 giờ.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">c) Nêu nhận xét về chuyển động của xe.</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Phương pháp giải:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Biểu thức tính tốc độ: <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac></math>" id="MathJax-Element-34-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-492" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-493" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-494" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-495" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-496" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-497" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-498" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) v: tốc độ chuyển động của vật (m/s)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) s: quãng đường đi được của vật (m)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">+) t: thời gian đi được quãng đường s của vật (s)</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Đổi đơn vị thời gian: 1 phút = <span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>1</mn><mrow class="MJX-TeXAtom-ORD"><mn>60</mn></mrow></mfrac><mi>h</mi></math>" id="MathJax-Element-35-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-499" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-500" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mfrac" id="MJXc-Node-501" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.849em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.276em; width: 1.2em;"><span class="mjx-mn" id="MJXc-Node-502" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span></span><span class="mjx-denominator" style="bottom: -0.591em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 1.2em;"><span class="mjx-texatom" id="MJXc-Node-503" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-504" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-505" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">60</span></span></span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.849em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.32em; margin: 0px; padding: 0px; vertical-align: -0.418em; width: 0px;"></span></span><span class="mjx-mi" id="MJXc-Node-506" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.461em 0px 0.278em; white-space: pre;">h</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>1</mn><mrow class="MJX-TeXAtom-ORD"><mn>60</mn></mrow></mfrac><mi>ℎ</mi></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><strong style="font-family: OpenSansBold; margin: 0px; padding: 0px;">Lời giải chi tiết:</strong></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">a) Quãng đường xe đi được trong các thời điểm chính là độ chênh lệch chỉ số của đồng hồ đo quãng đường, ta có bảng:</p><table border="1" cellpadding="0" cellspacing="0" style="border-spacing: 0px; margin: 0px 0px 1.4em; padding: 0px; vertical-align: middle; width: 585px;"><tbody style="margin: 0px; padding: 0px;"><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Thời điểm</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Số chỉ của đồng hồ đo quãng đường (km)</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">Quãng đường đi được tính từ lúc xuất phát (km)</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">6 giờ 30 phút</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">10200</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">0</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">7 giờ</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">10220</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">20</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">7 giờ 30 phút</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">10240</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">20</p></td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">8 giờ</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">10260</p></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><p align="center" style="font-size: 18px; line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">20</p></td></tr></tbody></table><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">b) Đổi 30 phút = 0,5h</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">- Tốc độ của xe từ lúc 6 giờ 30 phút đến 7 giờ là:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>20</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>0</mn><mo>,</mo><mn>5</mn></mrow></mfrac><mo>=</mo><mn>40</mn><mo stretchy="false">(</mo><mi>k</mi><mi>m</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>h</mi><mo stretchy="false">)</mo></math>" id="MathJax-Element-36-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-507" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-508" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-509" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-510" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-511" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-512" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-513" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-514" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-515" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 1.045em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.298em; width: 1.478em;"><span class="mjx-texatom" id="MJXc-Node-516" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-517" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-518" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">20</span></span></span></span></span><span class="mjx-denominator" style="bottom: -0.763em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 1.478em;"><span class="mjx-texatom" id="MJXc-Node-519" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-520" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-521" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">0</span></span><span class="mjx-mo" id="MJXc-Node-522" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn" id="MJXc-Node-523" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">5</span></span></span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 1.045em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.457em; margin: 0px; padding: 0px; vertical-align: -0.54em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-524" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-525" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">40</span></span><span class="mjx-mo" id="MJXc-Node-526" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">(</span></span><span class="mjx-mi" id="MJXc-Node-527" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.461em 0px 0.278em; white-space: pre;">k</span></span><span class="mjx-mi" id="MJXc-Node-528" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">m</span></span><span class="mjx-texatom" id="MJXc-Node-529" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-530" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mo" id="MJXc-Node-531" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">/</span></span></span></span><span class="mjx-mi" id="MJXc-Node-532" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.461em 0px 0.278em; white-space: pre;">h</span></span><span class="mjx-mo" id="MJXc-Node-533" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">)</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>20</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>0</mn><mo>,</mo><mn>5</mn></mrow></mfrac><mo>=</mo><mn>40</mn><mo stretchy="false">(</mo><mi>�</mi><mi>�</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>ℎ</mi><mo stretchy="false">)</mo></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">- Tốc độ của xe từ lúc 6 giờ 30 phút đến 7 giờ 30 phút là:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>40</mn></mrow><mn>1</mn></mfrac><mo>=</mo><mn>40</mn><mo stretchy="false">(</mo><mi>k</mi><mi>m</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>h</mi><mo stretchy="false">)</mo></math>" id="MathJax-Element-37-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-534" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-535" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-536" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-537" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-538" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-539" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-540" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-541" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-542" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.849em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.309em; width: 1.2em;"><span class="mjx-texatom" id="MJXc-Node-543" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-544" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-545" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">40</span></span></span></span></span><span class="mjx-denominator" style="bottom: -0.569em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 1.2em;"><span class="mjx-mn" id="MJXc-Node-546" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.849em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.328em; margin: 0px; padding: 0px; vertical-align: -0.402em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-547" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-548" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">40</span></span><span class="mjx-mo" id="MJXc-Node-549" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">(</span></span><span class="mjx-mi" id="MJXc-Node-550" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.461em 0px 0.278em; white-space: pre;">k</span></span><span class="mjx-mi" id="MJXc-Node-551" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">m</span></span><span class="mjx-texatom" id="MJXc-Node-552" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-553" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mo" id="MJXc-Node-554" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">/</span></span></span></span><span class="mjx-mi" id="MJXc-Node-555" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.461em 0px 0.278em; white-space: pre;">h</span></span><span class="mjx-mo" id="MJXc-Node-556" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">)</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>40</mn></mrow><mn>1</mn></mfrac><mo>=</mo><mn>40</mn><mo stretchy="false">(</mo><mi>�</mi><mi>�</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>ℎ</mi><mo stretchy="false">)</mo></math></span></span></p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;">- Tốc độ của xe từ lúc 6 giờ 30 phút đến 8 giờ là:</p><p style="line-height: 26px; margin: 0px 0px 12px; padding: 0px; word-break: normal;"><span class="mjx-chtml MathJax_CHTML" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mi>s</mi><mi>t</mi></mfrac><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>60</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>1</mn><mo>,</mo><mn>5</mn></mrow></mfrac><mo>=</mo><mn>40</mn><mo stretchy="false">(</mo><mi>k</mi><mi>m</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>h</mi><mo stretchy="false">)</mo></math>" id="MathJax-Element-38-Frame" role="presentation" style="border: 0px; direction: ltr; display: inline-block; float: none; font-size: 21.78px; line-height: 0; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 1px 0px; position: relative; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><span aria-hidden="true" class="mjx-math" id="MJXc-Node-557" style="border-collapse: separate; border-spacing: 0px; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-558" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mi" id="MJXc-Node-559" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">v</span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-560" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-561" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 0.473em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.062em; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-562" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">s</span></span></span><span class="mjx-denominator" style="bottom: -0.54em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 0.669em;"><span class="mjx-mi" id="MJXc-Node-563" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.416em 0px 0.278em; white-space: pre;">t</span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 0.473em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.133em; margin: 0px; padding: 0px; vertical-align: -0.382em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-564" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mfrac MJXc-space3" id="MJXc-Node-565" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-box MJXc-stacked" style="box-sizing: content-box !important; display: inline-block; height: 0px; margin: 0px; padding: 0px 0.12em; position: relative; width: 1.045em;"><span class="mjx-numerator" style="box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; top: -1.298em; width: 1.478em;"><span class="mjx-texatom" id="MJXc-Node-566" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-567" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-568" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">60</span></span></span></span></span><span class="mjx-denominator" style="bottom: -0.763em; box-sizing: content-box !important; display: block; font-size: 15.3985px; margin: 0px; padding: 0px; position: absolute; text-align: center; width: 1.478em;"><span class="mjx-texatom" id="MJXc-Node-569" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px; text-align: left;"><span class="mjx-mrow" id="MJXc-Node-570" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mn" id="MJXc-Node-571" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px 0.324em; white-space: pre;">1</span></span><span class="mjx-mo" id="MJXc-Node-572" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: -0.181em 0px 0px; padding: 0px 0px 0.553em; white-space: pre;">,</span></span><span class="mjx-mn" id="MJXc-Node-573" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">5</span></span></span></span></span><span class="mjx-line" style="border-bottom: 1.3px solid; box-sizing: content-box !important; display: block; height: 0px; margin: 0px; padding: 0px; position: absolute; top: -0.28em; width: 1.045em;"></span></span><span class="mjx-vsize" style="box-sizing: content-box !important; display: inline-block; height: 1.457em; margin: 0px; padding: 0px; vertical-align: -0.54em; width: 0px;"></span></span><span class="mjx-mo MJXc-space3" id="MJXc-Node-574" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.094em 0px 0.324em; white-space: pre;">=</span></span><span class="mjx-mn MJXc-space3" id="MJXc-Node-575" style="box-sizing: content-box !important; display: inline-block; margin: 0px 0px 0px 0.278em; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.37em 0px; white-space: pre;">40</span></span><span class="mjx-mo" id="MJXc-Node-576" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">(</span></span><span class="mjx-mi" id="MJXc-Node-577" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.461em 0px 0.278em; white-space: pre;">k</span></span><span class="mjx-mi" id="MJXc-Node-578" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.232em 0px 0.278em; white-space: pre;">m</span></span><span class="mjx-texatom" id="MJXc-Node-579" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mrow" id="MJXc-Node-580" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-mo" id="MJXc-Node-581" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">/</span></span></span></span><span class="mjx-mi" id="MJXc-Node-582" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-math-I" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-math-I, MJXc-TeX-math-Ix, MJXc-TeX-math-Iw; margin: 0px; padding: 0.461em 0px 0.278em; white-space: pre;">h</span></span><span class="mjx-mo" id="MJXc-Node-583" style="box-sizing: content-box !important; display: inline-block; margin: 0px; padding: 0px;"><span class="mjx-char MJXc-TeX-main-R" style="box-sizing: content-box !important; display: block; font-family: MJXc-TeX-main-R, MJXc-TeX-main-Rw; margin: 0px; padding: 0.461em 0px 0.599em; white-space: pre;">)</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation" style="border: 0px !important; clip: rect(1px, 1px, 1px, 1px); display: block !important; height: 1px !important; left: 0px; margin: 0px; overflow: hidden !important; padding: 1px 0px 0px !important; position: absolute !important; top: 0px; user-select: none; width: 1px !important;"><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>�</mi><mo>=</mo><mfrac><mi>�</mi><mi>�</mi></mfrac><mo>=</mo><mfrac><mrow class="MJX-TeXAtom-ORD"><mn>60</mn></mrow><mrow class="MJX-TeXAtom-ORD"><mn>1</mn><mo>,</mo><mn>5</mn></mrow></mfrac><mo>=</mo><mn>40</mn><mo stretchy="false">(</mo><mi>�</mi><mi>�</mi><mrow class="MJX-TeXAtom-ORD"><mo>/</mo></mrow><mi>ℎ</mi><mo stretchy="false">)</mo></math></span></span></p></div><p><span style="background-color: white; font-family: OpenSans, Tahoma, Helvetica, sans-serif; font-size: 18px; text-align: justify;">c) Nhận xét: xe chuyển động thẳng đều trên cả quãng đường.</span> </p><p><br /></p><p><br /></p><p><br /></p>

Bài 10. Đo tốc độ trang 31, 32, 33 SBT Khoa học tự nhiên 7

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