Question

A steel rod bas a radius of 20 mm and a length of 2.0 m. A force of 62.8 kN stretches it along its length. Young's modulus of steel is 2.0 × 10^{11} N/m^2 . The longitudinal strain produced in the wire is _______ × 10^{-5}

Answer 1

$\begin{aligned} & Y=\frac{\text { stress }}{\text { strain }} \\\ & \Rightarrow \text { strain }=\frac{\text { stress }}{Y}=\frac{F}{A Y}=\frac{62.8 \times 1000}{\pi r^2 \times 2 \times 10^{11}}=\frac{62.8 \times 1000}{3.14 \times 400 \times 10^{-6} \times 2 \times 10^{11}}=\frac{200}{8} \times 10^{-5}=25 \times 10^{-5} \end{aligned}$