A uniform metal rod fixed at its ends of `2 mm^(2)` cross-section is cooled from `40^(@)C` to `20^(@)C`. The coefficient of the linear expansion of the rod is `12xx10^(-6) ` per degree celsius and its young's modulus of elasticity is `10^11 N//m^(2).` The energy stored per unit volume of the rod is

Options

A. `2880(J)/(m^3)`
B. `1500(J)/(m^3)`
C. `5760(J)/(m^3)`
D. `1440(J)/(m^3)`

Answer

A

Explanation

Energy Density`=(1)/(2)stressxx"strain"=(1)/(2)Y("strain")^2`
`=1880(J)/(m^3)`