Bài 22. Thực hành: Tổng hợp lực
Hướng dẫn giải Câu hỏi (Trang 86 SGK Vật lí 10, Bộ Kết nối tri thức)
<p><em><strong>Gắn đế nam ch&acirc;m l&ecirc;n bảng th&eacute;p, m&oacute;c sợi d&acirc;y cao su v&agrave;o đế nam ch&acirc;m, đặt hai lực kế</strong></em></p> <p><em><strong> l&ecirc;n bảng th&eacute;p v&agrave; m&oacute;c hai lực kế v&agrave;o đầu c&ograve;n lại của d&acirc;y cao su. Dịch chuyển hai lực kế </strong></em></p> <p><em><strong>để k&eacute;o sợi d&acirc;y cao su l&agrave;m d&acirc;y d&atilde;n ra một khoảng v&agrave; thảo luận:</strong></em></p> <p><em><strong>1. L&agrave;m thế n&agrave;o để hai lực&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-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;msub&gt;&lt;mover accent=&quot;true&quot;&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mo&gt;&amp;#x2192;&lt;/mo&gt;&lt;/mover&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msub&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-msub"><span class="mjx-base"><span id="MJXc-Node-4" class="mjx-mover"><span class="mjx-stack"><span class="mjx-over"><span id="MJXc-Node-6" class="mjx-mo"></span></span></span></span></span></span></span></span></span><math xmlns="http://www.w3.org/1998/Math/MathML"><mover><msub><mi mathvariant="bold">F</mi><mn mathvariant="bold">1</mn></msub><mo mathvariant="bold">&rarr;</mo></mover><mo mathvariant="bold">&nbsp;</mo><mi mathvariant="bold-italic">v</mi><mi mathvariant="bold-italic">&agrave;</mi><mo mathvariant="bold">&nbsp;</mo><mover><msub><mi mathvariant="bold">F</mi><mn mathvariant="bold">2</mn></msub><mo mathvariant="bold">&rarr;</mo></mover></math><math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mn></mn></msub></math>&nbsp;đồng quy?</strong></em></p> <p><em><strong>2. L&agrave;m thế n&agrave;o để thay thế t&aacute;c dụng của hai lực&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-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;msub&gt;&lt;mover accent=&quot;true&quot;&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mo&gt;&amp;#x2192;&lt;/mo&gt;&lt;/mover&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msub&gt;&lt;/math&gt;"><span id="MJXc-Node-15" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-16" class="mjx-mrow"><span id="MJXc-Node-17" class="mjx-msub"><span class="mjx-base"><span id="MJXc-Node-18" class="mjx-mover"><span class="mjx-stack"><span class="mjx-over"><span id="MJXc-Node-20" class="mjx-mo"></span></span></span></span></span></span></span></span></span><math xmlns="http://www.w3.org/1998/Math/MathML"><mover><msub><mi mathvariant="bold">F</mi><mn mathvariant="bold">1</mn></msub><mo mathvariant="bold">&rarr;</mo></mover><mo mathvariant="bold">&nbsp;</mo><mi mathvariant="bold-italic">v</mi><mi mathvariant="bold-italic">&agrave;</mi><mo mathvariant="bold">&nbsp;</mo><mover><msub><mi mathvariant="bold">F</mi><mn mathvariant="bold">2</mn></msub><mo mathvariant="bold">&rarr;</mo></mover></math><math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mn></mn></msub></math>&nbsp;bằng một lực&nbsp;<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-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;mover accent=&quot;true&quot;&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mo&gt;&amp;#x2192;&lt;/mo&gt;&lt;/mover&gt;&lt;/math&gt;"><span id="MJXc-Node-29" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-30" class="mjx-mrow"><span id="MJXc-Node-31" class="mjx-mover"><span class="mjx-stack"><span class="mjx-over"><span id="MJXc-Node-33" class="mjx-mo"></span></span></span></span></span></span><math xmlns="http://www.w3.org/1998/Math/MathML"><mover><mi mathvariant="bold">F</mi><mo mathvariant="bold">&rarr;</mo></mover><mo mathvariant="bold">&nbsp;</mo></math></span></strong></em></p> <p><em><strong><math xmlns="http://www.w3.org/1998/Math/MathML"><mover accent="true"><mo></mo></mover></math>&nbsp;m&agrave; d&acirc;y cao su vẫn d&atilde;n một đoạn v&agrave; hướng như ban đầu?</strong></em></p> <p><em><strong>3. L&agrave;m thế n&agrave;o x&aacute;c định tổng hợp của hai lực&nbsp;<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-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;msub&gt;&lt;mover accent=&quot;true&quot;&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mo&gt;&amp;#x2192;&lt;/mo&gt;&lt;/mover&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msub&gt;&lt;/math&gt;"><span id="MJXc-Node-34" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-35" class="mjx-mrow"><span id="MJXc-Node-36" class="mjx-msub"><span class="mjx-base"><span id="MJXc-Node-37" class="mjx-mover"><span class="mjx-stack"><span class="mjx-over"><span id="MJXc-Node-39" class="mjx-mo"></span></span></span></span></span></span></span></span></span><math xmlns="http://www.w3.org/1998/Math/MathML"><mover><msub><mi mathvariant="bold">F</mi><mn mathvariant="bold">1</mn></msub><mo mathvariant="bold">&rarr;</mo></mover><mo mathvariant="bold">&nbsp;</mo><mi mathvariant="bold-italic">v</mi><mi mathvariant="bold-italic">&agrave;</mi><mo mathvariant="bold">&nbsp;</mo><mover><msub><mi mathvariant="bold">F</mi><mn mathvariant="bold">2</mn></msub><mo mathvariant="bold">&rarr;</mo></mover></math><math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mn></mn></msub></math>?</strong></em></p> <p><span style="text-decoration: underline;"><em><strong>Lời giải:</strong></em></span></p> <p>1. C&aacute;ch để <span id="MathJax-Element-8-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;msub&gt;&lt;mover accent=&quot;true&quot;&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;mo&gt;&amp;#x2192;&lt;/mo&gt;&lt;/mover&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msub&gt;&lt;/math&gt;"><span id="MJXc-Node-48" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-49" class="mjx-mrow"><span id="MJXc-Node-50" class="mjx-msub"><span class="mjx-base"><span id="MJXc-Node-51" class="mjx-mover"><span class="mjx-stack"><span class="mjx-over"><span id="MJXc-Node-53" class="mjx-mo"></span></span></span></span></span></span></span></span></span><math xmlns="http://www.w3.org/1998/Math/MathML"><mover><msub><mi mathvariant="bold">F</mi><mn mathvariant="bold">1</mn></msub><mo mathvariant="bold">&rarr;</mo></mover><mo mathvariant="bold">&nbsp;</mo><mi mathvariant="bold-italic">v</mi><mi mathvariant="bold-italic">&agrave;</mi><mo mathvariant="bold">&nbsp;</mo><mover><msub><mi mathvariant="bold">F</mi><mn mathvariant="bold">2</mn></msub><mo mathvariant="bold">&rarr;</mo></mover></math><math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mn></mn></msub></math>&nbsp;đồng quy: Di chuyển hai lực kế sao cho d&acirc;y cao su v&agrave; c&aacute;c đoạn d&acirc;y</p> <p>chỉ song song với mặt phẳng v&agrave; t&acirc;m O của thước tr&ugrave;ng với giao điểm của sợi d&acirc;y v&agrave; d&acirc;y cao su.</p> <p>2. C&aacute;ch x&aacute;c định lực thay thế hai lực th&agrave;nh phần:</p> <p>+ Đ&aacute;nh dấu l&ecirc;n bảng sắt điểm A của đầu d&acirc;y cao su.</p> <p>+ Th&aacute;o một lực kế ra.</p> <p>+ Di chuyển lực kế c&ograve;n lại sao cho đầu d&acirc;y cao su tr&ugrave;ng với điểm A đ&atilde; đ&aacute;nh dấu.</p> <p>3. Sau khi bố tr&iacute; th&iacute; nghiệm như ở c&acirc;u 2 th&igrave; ta ghi lại đ&aacute;p &aacute;n của lực kế, đ&oacute; l&agrave; số chỉ của lực tổng</p> <p>hợp, thực hiện th&iacute; nghiệm th&ecirc;m &iacute;t nhất 2 lần.</p>
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