A brass rod of cross sectional area `1cm^2` and length `0.2m` is compressed lengthwise by a weight of `5kg`. If Young's modulus of elasticity of brass is `1xx10^(11)N//m^2` and `g=10m//sec^2` Then increase in the energy of the rod will be

Options

A. `10^-5J`
B. `2.5xx10^-5J`
C. `5xx10^-5J`
D. `2.5xx10^-4J`

Answer

B

Explanation

`U=(1)/(2)xx((str ess)^2)/(Y)xxvolume=(1)/(2)xx(F^2xxAxxL)/(A^2xxY)`
`=(1)/(2)xx(F^2L)/(AY)=(1)/(2)xx((50)^2xx0.2)/(1xx10^-4xx1xx10^(11))=2.5xx10^-5J`