On stretching a wire, the elastic energy stored pre unit volume is

On stretching a wire, the elastic energy stored per unit volume is,

When an elastic material with Young's modulus Y is subjected to a stretching stress, the elastic energy stored per unit volume of the material is

When an elastic material with Young's modulus Y is subjected to stretching stress S, the elastic energy stored per unit volume of the material is

When an elastic material with Young's modulus Y is subjected to stretching stress S, elastic energy stored per unit volume of the material is :

The elastic energy stored per units volume in a streched wire is

Derive an expression for the elastic energy stored per unit volume of a wire.