Medium INTEGER +4 / -1 PYQ · JEE Mains 2022

A string of area of cross-section $4 \mathrm{~mm}^{2}$ and length $0.5 \mathrm{~m}$ is connected with a rigid body of mass $2 \mathrm{~kg}$. The body is rotated in a vertical circular path of radius $0.5 \mathrm{~m}$. The body acquires a speed of $5 \mathrm{~m} / \mathrm{s}$ at the bottom of the circular path. Strain produced in the string when the body is at the bottom of the circle is _________ $\times 10^{-5}$.

(use Young's modulus $10^{11} \mathrm{~N} / \mathrm{m}^{2}$ and $\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^{2}$)

Answer (integer) 30

Solution

<p>$A = 4 \times {10^{ - 6}}$ m<sup>2</sup></p> <p>$l = 0.5$ m</p> <p>$m = 2$ kg</p> <p>${v_b} = 5$ m/s</p> <p>${T_b} = mg + m\left( {{{V_b^2} \over l}} \right)$</p> <p>$= 20 + 2 \times {{25} \over {{1 \over 2}}} = 120$ N</p> <p>$${{\Delta l} \over l} = {{{T_b}} \over A} \times {1 \over Y} = {{120} \over {4 \times {{10}^{ - 6}}}} \times {10^{ - 11}} = 30 \times {10^{ - 5}}$$</p>

About this question

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

This question is part of PrepWiser's free JEE Main question bank. 183 more solved questions on Properties of Solids and Liquids are available — start with the harder ones if your accuracy is >70%.

Drill 25 more like these. Every day. Free.

PrepWiser turns these solved questions into a daily practice loop. Chapter-wise drills, full mocks, AI doubt chat. No auto-renew.

Start free →