TRẦN NGỌC KHÁNH NHƯ

<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;">10.1Để đo tốc độ của một người chạy cự ly ngắn, ta cần những dụng cụ đo nào?A. Thước cuộn và đồng hồ bấm giây.B. Thước thẳng và đồng hồ treo tường.C. Đồng hồ đo thời gian hiện số kết nối với cổng quang điện.D. Cổng quang điện và thước cuộn.Phương pháp giải:+ 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.+ 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.Lời giải chi tiết:Chọn A.</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;">10.2Trong 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?A. Thước, cổng quang điện và đồng hồ bấm giây.B. Thước, đồng hồ đo thời gian hiện số kết nối với cổng quang điện.C. Thước và đồng hồ đo thời gian hiện số.D. Cổng quang điện và đồng hồ bấm giây.Phương pháp giải:+ 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.+ 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.Lời giải chi tiết:Chọn B.</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;">10.3Trong 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.Phương pháp giải:Biểu thức tính tốc độ: <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 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 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 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-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 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-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 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>+) v: tốc độ chuyển động của vật (m/s)+) s: quãng đường đi được của vật (m)+) t: thời gian đi được quãng đường s của vật (s)Đổi đơn vị độ dài: 1 cm = <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">1<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;">100<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 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>Lời giải chi tiết:Tóm tắt:s = 20 cm = <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">20<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;">100<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 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;">=0<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;">,2<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 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><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> t =  1,02 sv = ?Lời giải:Tốc độ chuyển động của xe là:<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 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 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 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-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 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-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 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;">=0<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;">,2<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;">1<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;">,02<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;">≈0<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;">,196<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 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 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 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 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 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></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;">10.4Xác định tốc độ của một người chạy cự li 100 m được mô tả trong hình dưới đây.                       <img src="https://img.loigiaihay.com/picture/2022/0808/13.png" style="height: auto; margin: 0px; max-height: 100%; max-width: 100%; padding: 0px;" />Phương pháp giải:Biểu thức tính tốc độ: <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 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 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 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-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 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-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 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>+) v: tốc độ chuyển động của vật (m/s)+) s: quãng đường đi được của vật (m)+) t: thời gian đi được quãng đường s của vật (s)Lời giải chi tiết:Tóm tắt:s = 100 mt =  22 sv = ?Lời giải:Tốc độ của người chạy cự li 100 m được mô tả trong hình là:<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 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 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 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-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 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-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 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;">=100<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;">22<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;">≈4<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;">,55<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 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 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 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 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 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></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;">10.5a) Để xác định tốc độ của một vật đang chuyển động, ta cần biết những thông tin gì?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.Phương pháp giải:Để đo tốc độ, người ta cần đo quãng đường s vật đi được và thời gian chuyển động t của vật.Lời giải chi tiết: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.b) Lập kế hoạch và tiến hành đo tốc độ chuyển động của một xe đồ chơi chạy pin.- Dụng cụ: tấm ván phẳng (hoặc mặt đất phẳng), thước, bút đánh dấu, đồng hồ bấm giây, xe đồ chơi chạy bằng pin.- Cách tiến hành:+ 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.+ 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.+ Thực hiện ba lần đo, lấy giá trị trung bình của các phép đo.- Báo cáo kết quả đo vào bảng sau:<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">Lần đo</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">Quãng đường(m)</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">Thời gian(s)</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">1</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><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 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;">s1<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>=</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><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 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;">t1<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>=</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">2</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><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 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;">s2<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>=</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><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 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;">t2<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>=</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">3</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><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 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;">s3<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>=</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><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 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;">t3<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>=</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">Giá trị trung bình</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><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 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 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 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 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 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;">s1<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 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;">s2<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 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;">s3<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;">3<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></td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195"><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 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 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 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 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 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-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;">t1<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 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;">t2<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 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;">t3<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;">3<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></td></tr></tbody></table>+ Dùng công thức <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 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 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 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-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 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-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 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 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-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 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 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 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-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 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 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 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></div> để tính tốc độ của xe đồ chơi chạy bằng pin.<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;">10.6Hình dưới đây mô tả một cách đo tốc độ chảy của dòng nước bằng vật nổi.a) Em cần những dụng cụ nào để thực hiện phép đo này?b) Mô tả cách đo tốc độ chảy của dòng nước.<img src="https://img.loigiaihay.com/picture/2022/0808/14.png" style="height: auto; margin: 0px; max-height: 100%; max-width: 100%; padding: 0px;" />Phương pháp giải:Để đo tốc độ, người ta cần đo quãng đường s vật đi được và thời gian chuyển động t của vật.Lời giải chi tiết: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.b) Cách đo tốc độ chảy của dòng nước:- Cắm mốc căng dây để đánh dấu vạch xuất phát và vạch đích.- Dùng thước dây đo độ dài quãng đường s vật đi được bằng cách đo khoảng cách giữa vạch xuất phát và vạch đích.- 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.- Tính tốc độ chảy của dòng nước bằng công thức: <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 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 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 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-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 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-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 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></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;">10.7Bảng dưới đây cho biết thông tin về thành tích bơi ở cự li 50 m của một số nữ vận động viên quốc tế.(Nguồn: <a href="http://www.fina.org/" style="color: #336699; margin: 0px; outline: 0px; padding: 0px; text-decoration-line: none;">http://www.fina.org</a>)<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">Nội dung bơi</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85">Thời gian bơi (s)</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="113">Tên vận động viên</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85">Quốc tịch</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="151">Sự kiện</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75">Tốc độ bơi (m/s)</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75">50 m bơi tự do</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85">22,93</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="113">Ramoni Kromowidjojo</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85">Hà Lan</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="151">World Cup 2017</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75">?</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75">50 m bơi ngửa</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85">25,27</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="113">Margaret Mc Neil</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85">Canada</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="151">Final World Swimming Championship 2021</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75">?</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75">50 m bơi bướm</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85">24,38</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="113">Therese Alshammar</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="85">Thụy Điển</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="151">World Cup 2009</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="75">?</td></tr></tbody></table></div>a) Tính tốc độ bơi của các vận động viên.b) Để đo tốc độ bơi của một người, em cần những dụng cụ gì?Phương pháp giải:Biểu thức tính tốc độ: <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 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 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 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-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 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-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 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>+) v: tốc độ chuyển động của vật (m/s)+) s: quãng đường đi được của vật (m)+) t: thời gian đi được quãng đường s của vật (s)Lời giải chi tiết:Tóm tắt:<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 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;">s1<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 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;">s2<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 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;">s3<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;">=50<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>m<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 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;">t1<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;">=22<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;">,93<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>s, <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 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;">v1<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>=?<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 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;">t2<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;">=25<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;">,27<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>s, <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 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;">v2<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>=?<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 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;">t3<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;">=24<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;">,38<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>s, <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 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;">v3<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>=?Lời giải:a) Tốc độ bơi của vận động viên người Hà Lan là:<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 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 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 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-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 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-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 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 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 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;">50<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;">22<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;">,93<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;">≈2<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;">,18<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 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 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 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 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 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>Tốc độ bơi của vận động viên người Canada là:<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 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 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 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-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 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-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 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 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 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;">50<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;">25<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;">,27<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;">≈1<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;">,98<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 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 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 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 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 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>Tốc độ bơi của vận động viên người Thụy Điển là:<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 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 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 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-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 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-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 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 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 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;">50<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;">24<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;">,38<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;">≈2<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;">,05<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 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 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 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 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 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>b) Để đo tốc độ bơi của một người, em cần những dụng cụ là: Thước dây, đồng hồ bấm giây.</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;">10.8Hình 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.<img src="https://img.loigiaihay.com/picture/2022/0808/15.png" style="height: auto; margin: 0px; max-height: 100%; max-width: 100%; padding: 0px;" />Hãy trình bày cách tính tốc độ lan truyền âm thanh trong không khí.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.Phương pháp giải:Biểu thức tính tốc độ: <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 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 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 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-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 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-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 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>+) v: tốc độ chuyển động của vật (m/s)+) s: quãng đường đi được của vật (m)+) t: thời gian đi được quãng đường s của vật (s)Lời giải chi tiết:Tóm tắt:s = 1,2 mt = 0,0035 sv=?Lời giải:a) Cách tính tốc độ truyền âm thanh:- Đo khoảng cách s giữa hai micro.- Đọc giá trị thời gian t hiển thị trên màn hình bộ đếm thời gian.- Tính tốc độ theo công thức: <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 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 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 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-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 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-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 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>b) Tốc độ lan truyền âm thanh trong không khí:<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 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 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 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-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 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-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 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 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;">=1<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;">,2<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;">0<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;">,0035<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;">≈342<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;">,86<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 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 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 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 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 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></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;">10.9Để 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.                       <img src="https://img.loigiaihay.com/picture/2022/0808/16.png" style="height: auto; margin: 0px; max-height: 100%; max-width: 100%; padding: 0px;" />a) Hãy trình bày cách tính tốc độ gió.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.Phương pháp giải:Biểu thức tính tốc độ: <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 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 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 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-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 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-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 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>+) v: tốc độ chuyển động của vật (m/s)+) s: quãng đường đi được của vật (m)+) t: thời gian đi được quãng đường s của vật (s)Đổi đơn vị độ dài: 1 cm =<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">1<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;">100<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 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>Lời giải chi tiết:Tóm tắt:R = 60 cm = 0,6 mn = 20 vòngt = 4,2 sv=?Lời giải:Quãng đường tại 1 điểm trên 1 cánh chong chóng khi quay được 1 vòng ( tương đương chu vi chong chóng) là:            0,6.3,14=1,884(m)Quãng đường mà điểm đó đi được trong 20 vòng là:            1,884.20=37,68(m)Tốc độ gió là:<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 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 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 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-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 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-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 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;">=37<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;">,68<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;">4<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;">,2<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;">≈8<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;">,97<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>(m/s)</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;">10.10Bảng 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 ).<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">Thời điểm</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">Số chỉ của đồng hồ đo quãng đường (km)</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">Quãng đường đi được tính từ lúc xuất phát (km)</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">6 giờ 30 phút</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">10200</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">0</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">7 giờ</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">10220</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">?</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">7 giờ 30 phút</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">10240</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">?</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">8 giờ</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">10260</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">?</td></tr></tbody></table>a) Xác định quãng đường xe đi được tính từ lúc xuất phát cho đến các thời điểm đã cho và điền vào bảng.b) Tính tốc độ của xe trong các khoảng thời gian sau:    - Từ lúc 6 giờ 30 phút đến 7 giờ.    - Từ lúc 6 giờ 30 phút đến 7 giờ 30 phút.    - Từ lúc 6 giờ 30 phút đến 8 giờ.c) Nêu nhận xét về chuyển động của xe.Phương pháp giải:Biểu thức tính tốc độ: <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 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 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 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-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 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-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 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>+) v: tốc độ chuyển động của vật (m/s)+) s: quãng đường đi được của vật (m)+) t: thời gian đi được quãng đường s của vật (s)Đổi đơn vị thời gian: 1 phút = <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">1<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;">60<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 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>Lời giải chi tiết: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:<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">Thời điểm</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">Số chỉ của đồng hồ đo quãng đường (km)</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">Quãng đường đi được tính từ lúc xuất phát (km)</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">6 giờ 30 phút</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">10200</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">0</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">7 giờ</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">10220</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">20</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">7 giờ 30 phút</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">10240</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">20</td></tr><tr style="margin: 0px; padding: 0px;"><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">8 giờ</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">10260</td><td style="margin: 0px; padding: 5px; vertical-align: top;" valign="top" width="195">20</td></tr></tbody></table>b) Đổi 30 phút = 0,5h- Tốc độ của xe từ lúc 6 giờ 30 phút đến 7 giờ là:<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 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 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 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-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 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-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 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 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;">20<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;">0<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;">,5<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;">=40<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 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 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 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 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 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 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>- Tốc độ của xe từ lúc 6 giờ 30 phút đến 7 giờ 30 phút là:<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 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 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 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-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 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-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 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;">=40<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;">1<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;">=40<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 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 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 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 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 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 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>- Tốc độ của xe từ lúc 6 giờ 30 phút đến 8 giờ là:<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 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 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 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-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 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-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 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 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;">60<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;">1<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;">,5<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;">=40<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 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 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 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 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 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 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></div>c) Nhận xét: xe chuyển động thẳng đều trên cả quãng đường.

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

10.1 Để đo tốc độ của một người chạy cự ly ngắn, ta cần những dụng cụ đo nào? A. Thước cuộn và đồng hồ bấm giây. B. Thước thẳng và đồng hồ t...

+ Đọc thêm »