Question 240: Properties of Matter

Question

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 $$2 	imes 10^{11} \mathrm{~N} \mathrm{~m}^{-2}$$. Neglecting friction, the longitudinal strain on wire $$B$$ is ________ $$	imes 10^{-4}$$. (Take $$\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^2$$)

Accepted Answer

$$\begin{aligned}
& a=\frac{10}{3} \mathrm{~m} / \mathrm{s}^2 \\
& 30-T_1=3 	imes a \\
& T_1=20 \mathrm{~N} \\
& 	ext { strain }=\frac{	ext { stress }}{Y} \\
& =2 	imes 10^{-4}
\end{aligned}$$

Properties of Matter

Choose the correct answer: