Question

explain the formula of elastic potential energy stored per unit vol. of astrained body

Answer 1

Elastic potential energy: It is the energy of an object associated with the state of extension or compression.
For a spring, E=$\frac{1}{2}k{x}^2$,
For a wire: if the weight is suspended from a wire of length L having area of cross-section =A, then the elastic potential energy per unit volume = $\frac{1}{2}\times stress\times strain=\frac{1\times mg}{2\times A}\times \frac{x}{L}=\frac{1\times Y\times (strain{)}^2}{2}$