$3\mathrm{.}1-4($a$)$ Consider volume $V$ of a differential element and its change $V$ under stress.

Show that $\frac{V}{V}={}_x+{}_y+{}_z$ if strains are small. ${}_x={}_y={}_z=p$

$($b$)$ Let hydrostatic pressure $p$ be applied. Obtain an expression for $\frac{\frac{V}{V}}{p}.$

$($c$)$ Hence, show that a rubberlike material is almost incompressible. $)=(0\mathrm{.}5$