A steel wire of length 5 m and area of cross-section `4 mm^(2)` is stretched by 2 mm by the application of a force. If young's modulus of steel is `2xx10^(11)N//m^(2),` then the energy stored in the wire is

Options

A. 0.64
B. 0.16 J
C. 0.32 J
D. 1.28 J

Answer

C

Explanation

`E=(1)/(2)xx y xx ("strain")^(2) xx "volume" `
`=(2xx10^(11) xx 4 xx 10^(-6) xx 5)/(2xx25)=0.32 J`.