JEE Main 2026 — Mechanical Properties of Solids Question with Solution

A string $A$ of length $0.314$ m and Young's modulus $2\times 10^{10}$ N/m${}^2$ is connected to another string $B$ of length and Young's modulus both twice of those of $A$. This series combination of strings is then suspended from a rigid support and its free end is fixed to a load of mass $0.8$ kg. The net change in length of the combination is _____ mm. (radius of both the strings is $0.2$ mm and acceleration due to gravity $=10$ m/s${}^2$) (Mass of both strings is to be neglected as compared to the mass of load)