Bài 20. Động học của chuyển động tròn
Hướng dẫn giải Thảo luận 4 (Trang 127 SGK Vật lý, Bộ Chân trời sáng tạo)
<p>Ta cần lưu &yacute; g&igrave; khi sử dụng c&ocirc;ng thức (20.2) để t&iacute;nh độ lớn của một g&oacute;c chắn cung tr&ograve;n c&oacute; chiều d&agrave;i s.</p> <p><strong>Lời giải chi tiết:</strong></p> <p>Lưu &yacute; khi sử dung biểu thức&nbsp;<span id="MathJax-Element-4-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 19.36px; 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; position: relative;" tabindex="0" role="presentation" data-mathml="&lt;math xmlns=&quot;http://www.w3.org/1998/Math/MathML&quot;&gt;&lt;mi&gt;s&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;&amp;#x03B1;&lt;/mi&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;/math&gt;"><span id="MJXc-Node-49" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-50" class="mjx-mrow"><span id="MJXc-Node-51" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I">s</span></span><span id="MJXc-Node-52" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R">=</span></span><span id="MJXc-Node-53" class="mjx-mi MJXc-space3"><span class="mjx-char MJXc-TeX-math-I">&alpha;</span></span><span id="MJXc-Node-54" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R">.</span></span><span id="MJXc-Node-55" class="mjx-mi MJXc-space1"><span class="mjx-char MJXc-TeX-math-I">R</span></span></span></span></span>&nbsp;l&agrave; g&oacute;c &alpha; c&oacute; đơn vị l&agrave; radian.</p> <p>Với&nbsp;<span id="MathJax-Element-5-Frame" class="mjx-chtml MathJax_CHTML" style="margin: 0px; padding: 1px 0px; display: inline-block; line-height: 0; text-indent: 0px; text-align: left; text-transform: none; font-style: normal; font-weight: normal; font-size: 19.36px; 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; position: relative;" tabindex="0" role="presentation" data-mathml="&lt;math xmlns=&quot;http://www.w3.org/1998/Math/MathML&quot;&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;msup&gt;&lt;mi&gt;&amp;#x03B1;&lt;/mi&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;&amp;#x03B1;&lt;/mi&gt;&lt;mo stretchy=&quot;false&quot;&gt;(&lt;/mo&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;mo stretchy=&quot;false&quot;&gt;)&lt;/mo&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mfrac&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;msup&gt;&lt;mrow class=&quot;MJX-TeXAtom-ORD&quot;&gt;&lt;mn&gt;180&lt;/mn&gt;&lt;/mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mi&gt;&amp;#x03C0;&lt;/mi&gt;&lt;/mfrac&gt;&lt;/math&gt;"><span id="MJXc-Node-56" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-57" class="mjx-mrow"><span id="MJXc-Node-58" class="mjx-texatom"><span id="MJXc-Node-59" class="mjx-mrow"><span id="MJXc-Node-60" class="mjx-msubsup"><span class="mjx-base"><span id="MJXc-Node-61" class="mjx-mi"></span></span></span></span></span><math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>&#945;</mi><mn>0</mn></msup><mo>=</mo><mi>&#945;</mi><mo>(</mo><mi>r</mi><mi>a</mi><mi>d</mi><mo>)</mo><mo>.</mo><mfrac><msup><mn>180</mn><mn>0</mn></msup><mi>&#960;</mi></mfrac></math><span id="MJXc-Node-71" class="mjx-mfrac MJXc-space1"><span class="mjx-box MJXc-stacked"><span class="mjx-denominator"><span id="MJXc-Node-81" class="mjx-mi"></span></span></span></span></span></span></span></p>
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