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. $7.5\times {10}^{-3}J$
• C. $9.3\times {10}^{-2}J$
• D. $2.5\times {10}^{-2}J$

Answer 1

The correct option is B $7.5\times {10}^{-3}J$

$\begin{array}{cc}\text{Work done in stretching of a wire}& =\frac{1}{2}Fl\\ & =\frac{1}{2}mgl\\ & =\frac{1}{2}\left(0.5\right)\left(10\right)\times (3\times {10}^{-3})\\ & =7.5\times {10}^{-3}\\ \text{Hence answer is}B& \end{array}$