Question

A wire of length $50\, cm$ and cross-sectional area of $1 \, mm ^2$ is extended by $1 \, mm$. The required work (in joule) will be $\left( Y =2 \times 10^{10} \, Nm ^{-2}\right)$

Answer 1

If side of the cube is $L$ then $V=L^3 \Rightarrow \frac{d V}{V}=3 \frac{d L}{L}$
$\therefore \%$ change in volume $=3 \times(\%$ change in length $)$
$=3 \times 1 \%=3 \%$
$\therefore$ Bulk strain $\frac{\Delta V}{V}=0.03$