Bài 1: Chuyển động tròn
Hướng dẫn giải Câu hỏi 3 (Trang 109 SGK Vật lý 10, Bộ Cánh diều)
<p>Dựa v&agrave;o đơn vị SI của c&aacute;c đại lượng, h&atilde;y chứng tỏ t&iacute;nh đ&uacute;ng đắn của biểu thức (4) v = &omega;.r</p> <p><strong>Lời giải:</strong></p> <p>Giả sử một vật đi hết một v&ograve;ng tr&ograve;n với thời gian T (s)</p> <p>Ta c&oacute; tốc độ g&oacute;c của vật l&agrave;:<strong>&nbsp;<span id="MathJax-Element-1-Frame" class="mjx-chtml MathJax_CHTML" style="box-sizing: border-box; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 21.78px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;" tabindex="0" role="presentation" data-mathml="&lt;math xmlns=&quot;http://www.w3.org/1998/Math/MathML&quot;&gt;&lt;mi&gt;&amp;#x3C9;&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mi&gt;&amp;#x3C0;&lt;/mi&gt;&lt;/mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mfrac&gt;&lt;/math&gt;"><span id="MJXc-Node-1" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-2" class="mjx-mrow"><span id="MJXc-Node-3" class="mjx-mi"></span></span></span><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>&omega;</mi><mo>=</mo><mfrac><mrow><mn>2</mn><mi mathvariant="normal">&pi;</mi></mrow><mi>T</mi></mfrac></math><math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mi></mi></mfrac></math></span>&nbsp;</strong>thay v&agrave;o (4) ta được:</p> <p><span id="MathJax-Element-2-Frame" class="mjx-chtml MathJax_CHTML" style="box-sizing: border-box; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 21.78px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;" tabindex="0" role="presentation" data-mathml="&lt;math xmlns=&quot;http://www.w3.org/1998/Math/MathML&quot;&gt;&lt;mi&gt;v&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mi&gt;&amp;#x3C0;&lt;/mi&gt;&lt;/mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mfrac&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;/math&gt;"><span id="MJXc-Node-10" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-11" class="mjx-mrow"><span id="MJXc-Node-12" class="mjx-mi"></span></span></span><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>v</mi><mo>=</mo><mfrac><mrow><mn>2</mn><mi>&pi;</mi><mi>T</mi></mrow><mi>r</mi></mfrac></math><math xmlns="http://www.w3.org/1998/Math/MathML"><mi></mi></math></span></p> <p>Theo đơn vị SI của c&aacute;c đại lượng:</p> <p>+ T l&agrave; thời gian đơn vị l&agrave; gi&acirc;y (s)</p> <p>+ r l&agrave; b&aacute;n k&iacute;nh đơn vị l&agrave; m&eacute;t (m)</p> <p>+&nbsp;<span id="MathJax-Element-3-Frame" class="mjx-chtml MathJax_CHTML" style="box-sizing: border-box; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 21.78px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;" tabindex="0" role="presentation" data-mathml="&lt;math xmlns=&quot;http://www.w3.org/1998/Math/MathML&quot;&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mi&gt;&amp;#x3C0;&lt;/mi&gt;&lt;/math&gt;"><span class="MJX_Assistive_MathML" role="presentation"><math xmlns="http://www.w3.org/1998/Math/MathML"><mn>2</mn><mi>&pi;</mi></math></span></span>&nbsp;l&agrave; hằng số</p> <p><span id="MathJax-Element-4-Frame" class="mjx-chtml MathJax_CHTML" style="box-sizing: border-box; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 21.78px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;" tabindex="0" role="presentation" data-mathml="&lt;math xmlns=&quot;http://www.w3.org/1998/Math/MathML&quot;&gt;&lt;mo&gt;&amp;#x21D2;&lt;/mo&gt;&lt;/math&gt;"><span id="MJXc-Node-25" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-26" class="mjx-mrow"><span id="MJXc-Node-27" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">&rArr;</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation"><math xmlns="http://www.w3.org/1998/Math/MathML"><mo>&rArr;</mo></math></span></span>&nbsp;v = hằng số.<span id="MathJax-Element-5-Frame" class="mjx-chtml MathJax_CHTML" style="box-sizing: border-box; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 21.78px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;" tabindex="0" role="presentation" data-mathml="&lt;math xmlns=&quot;http://www.w3.org/1998/Math/MathML&quot;&gt;&lt;mfrac&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/mfrac&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mtext&gt;&amp;#x2009;&lt;/mtext&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;/math&gt;"><span id="MJXc-Node-28" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-29" class="mjx-mrow"><span id="MJXc-Node-30" class="mjx-mfrac"><span class="mjx-box MJXc-stacked"><span class="mjx-numerator"><span id="MJXc-Node-31" class="mjx-mn"></span></span></span></span></span></span><math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>1</mn><mi>s</mi></mfrac><mo>.</mo><mi>m</mi><mo>=</mo><mi>m</mi><mo>/</mo><mi>s</mi></math><math xmlns="http://www.w3.org/1998/Math/MathML"><mi></mi></math></span></p> <p><span id="MathJax-Element-6-Frame" class="mjx-chtml MathJax_CHTML" style="box-sizing: border-box; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 21.78px; letter-spacing: normal; overflow-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; margin: 0px; padding: 1px 0px; position: relative;" tabindex="0" role="presentation" data-mathml="&lt;math xmlns=&quot;http://www.w3.org/1998/Math/MathML&quot;&gt;&lt;mo&gt;&amp;#x21D2;&lt;/mo&gt;&lt;/math&gt;"><span id="MJXc-Node-40" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-41" class="mjx-mrow"><span id="MJXc-Node-42" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">&rArr;</span></span></span></span><span class="MJX_Assistive_MathML" role="presentation"><math xmlns="http://www.w3.org/1998/Math/MathML"><mo>&rArr;</mo></math></span></span>&nbsp;thỏa m&atilde;n đơn vị của vận tốc</p>
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