Q 11-08-084JEE MainJEE Main 2021 (20 Jul, Shift 2)Easy
The length of a metal wire is $\ell_1$, when the tension in it is $T_1$ and is $\ell_2$ when the tension is $T_2$. The natural length of the wire is:
Answer: (B) $\frac{\ell_1T_2 - \ell_2T_1}{T_2 - T_1}$
$\ell_1 = \ell_0 + cT_1$ and $\ell_2 = \ell_0 + cT_2$. Eliminating $c$: $T_2(\ell_1 - \ell_0) = T_1(\ell_2 - \ell_0)$
$$\ell_0 = \frac{\ell_1T_2 - \ell_2T_1}{T_2 - T_1}$$
Solution by Sreeraj P, M.Sc Physics