Question

A mass of $0.5kg$ is suspended from wire, then length of wire increase by $3mm$ then find out work done:

• A. $4.5\times {10}^{-3}J$
• B. $7.3\times {10}^{-3}J$
• C. $9.3\times {10}^{-2}J$
• D. $2.5\times {10}^{-2}J$

Answer 1

The correct option is B $7.3\times {10}^{-3}J$

$\begin{array}{c}\text{Given mass suspended}=0.5kg\\ \text{elongation of wire}=3mm\end{array}$

$\begin{array}{cc}\text{Work done}& =\frac{1}{2}\times \left(mg\right)\times \Delta \ell \\ & =\frac{1}{2}\times \frac{1}{2}\times 9.8\times 3\times {10}^{-3}\\ & =7.35\times {10}^{-3}J\end{array}$