What is the work done per unit volume when a steel wire is stretched by `0.2%` of its original length ? (Young's modulus of steel is `2xx10^(11)N//m^(2)`)

Options

A. `2xx10^(5)J//m^(3)`
B. `4 xx 10^(5)J//m^(3)`
C. `1//2 xx 10^(5)J//m^(3)`
D. `3//4 xx 10^(5) J//m^(3)`

Answer

B

Explanation

`U_(1)=(1)/(2)" Stress" xx "Strain"=(1)/(2) xx ("Strain")^(2)y`