Derive expression for elastic potential energy density $u = \frac{1}{2} \times \text{stress} \times \text{strain}$ stored in a stretched wire.
2.
A spherical ball of volume $V=0.5\text{ m}^3$ is subjected to a uniform pressure $P=10^7\text{ Pa}$. If Bulk modulus $B = 1.6 \times 10^{11}\text{ Pa}$, find volume change $\Delta V$.
