A metal wire of length L, area of cross-section A and young's modulus `Y` is stretched by a variable force `F` such that `F` is always slightly greater than the elastic forces of resistance in the wire. When the elongation of the wire is `l`

Options

A. the work done by `F` is `(YA^(2))/(L)`
B. the work done by `F` is `(Yal^(2))/(2L)`
C. the elastic potential energy stored in the wire is `(Yal^(2))/(2L)`
D. heat is produced during the elongation

Answer

C

Explanation

`W = -Delta U = (1)/(2)Kx^(2) = (1)/(2)(AY)/(L)l^(2)`