Q 11-08-065JEE MainJEE Main 2023 (1 Feb, Shift 2)Easy
The Young's modulus of a steel wire of length $6$ m and cross-sectional area $3\ \text{mm}^2$ is $2\times10^{11}\ \text{N m}^{-2}$. The wire is suspended from its support on a given planet. A block of mass $4$ kg is attached to the free end of the wire. The acceleration due to gravity on the planet is $\dfrac14$ of its value on the earth. The elongation of wire is (take $g$ on the earth $=10\ \text{m s}^{-2}$)
Answer: (C) $0.1\ \text{mm}$
$\Delta L=\dfrac{FL}{AY}=\dfrac{4\times2.5\times6}{3\times10^{-6}\times2\times10^{11}}=10^{-4}\ \text{m}=0.1$ mm.
Solution by Sreeraj P, M.Sc Physics