Mechanical Properties Of Solids Question 7
Question 7 - 2024 (30 Jan Shift 1)
Each of three blocks P, Q and R shown in figure has a mass of $3 \mathrm{~kg}$. Each of the wire A and B has crosssectional area $0.005 \mathrm{~cm}^{2}$ and Young’s modulus $2 \times 10^{11} \mathrm{~N} \mathrm{~m}^{-2}$. Neglecting friction, the longitudinal strain on wire $\mathrm{B}$ is $\times 10^{-4}$. (Take $\left.\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^{2}\right)$
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Answer: (2)
Solution:
$a=\frac{10}{3} \mathrm{~m} / \mathrm{s}^{2}$
$30-T_{1}=3 \times a$
$T_{1}=20 \mathrm{~N}$
strain $=\frac{\text { stress }}{Y}$
$=2 \times 10^{-4}$
