Q 11-08-063JEE MainJEE Main 2023 (10 Apr, Shift 1)Medium
Two wires each of radius $0.2$ cm and negligible mass, one made of steel and the other made of brass are loaded as shown in the figure. The elongation of the steel wire is ______ $\times10^{-6}$ m. [Young's modulus for steel $=2\times10^{11}\ \text{N m}^{-2}$ and $g=10\ \text{m s}^{-2}$]
Numerical value type. Enter your answer.
Answer: 20
The steel wire carries both blocks: $T=(2+1.14)\times10=31.4$ N. $A=\pi(2\times10^{-3})^2=1.256\times10^{-5}\ \text{m}^2$.
$$\Delta L=\frac{TL}{AY}=\frac{31.4\times1.6}{1.256\times10^{-5}\times2\times10^{11}}=2\times10^{-5}\ \text{m}=20\times10^{-6}\ \text{m}$$
Solution by Sreeraj P, M.Sc Physics