Medium INTEGER +4 / -1 PYQ · JEE Mains 2023

The length of a wire becomes $l_{1}$ and $l_{2}$ when $100 \mathrm{~N}$ and $120 \mathrm{~N}$ tensions are applied respectively. If $10 ~l_{2}=11~ l_{1}$, the natural length of wire will be $\frac{1}{x} ~l_{1}$. Here the value of $x$ is _____________.

Answer (integer) 2

Solution

<p>Given:</p> <ol> <li>When tension $T_1 = 100 \mathrm{~N}$, extension $= l_1 - l_0$.</li> <li>When tension $T_2 = 120 \mathrm{~N}$, extension $= l_2 - l_0$.</li> </ol> <p>Now, let&#39;s write the equations using Hooke&#39;s Law:</p> <p>$100 = k(l_1 - l_0)$</p> <p>$120 = k(l_2 - l_0)$</p> <p>Divide the first equation by the second equation:</p> <p>$\frac{5}{6} = \frac{l_1 - l_0}{l_2 - l_0}$</p> <p>Given the relationship between $l_1$ and $l_2$:</p> <p>$10l_2 = 11l_1$</p> <p>Now, let&#39;s solve for $l_0$:</p> <p>$5l_2 - 5l_0 = 6l_1 - 6l_0$</p> <p>$l_0 = 6l_1 - 5l_2$</p> <p>Substitute the relationship between $l_1$ and $l_2$:</p> <p>$l_0 = 6l_1 - 5\left(\frac{11l_1}{10}\right)$</p> <p>$l_0 = 6l_1 - \frac{11l_1}{2}$</p> <p>$l_0 = \frac{l_1}{2}$</p> <p>Therefore, the natural length of the wire is $\frac{1}{x}l_1 = \frac{2}{1}l_1 = 2l_1$. <br/><br/>The value of $x$ is $2$.</p>

About this question

Subject: Physics · Chapter: Properties of Solids and Liquids · Topic: Elasticity

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