JEE MAIN - Physics (2024 - 30th January Morning Shift - No. 29)
Each of three blocks $$\mathrm{P}, \mathrm{Q}$$ and $$\mathrm{R}$$ shown in figure has a mass of $$3 \mathrm{~kg}$$. Each of the wires $$\mathrm{A}$$ and $$\mathrm{B}$$ has cross-sectional 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 $$B$$ is ________ $$\times 10^{-4}$$. (Take $$\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^2$$)
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Answer
2
Explanation
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$$\begin{aligned} & a=\frac{10}{3} \mathrm{~m} / \mathrm{s}^2 \\\\ & 30-T_1=3 \times a \\\\ & T_1=20 \mathrm{~N} \\\\ & \text { strain }=\frac{\text { stress }}{Y} \\\\ & =2 \times 10^{-4} \end{aligned}$$
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