When a block of mass M is suspended by a long wire of length L, the length of the wire becomes (L+l). The elastic potential energy stored in the extended wire is

Options

A. Mgl
B. MgL
C. `(1)/(2)Mgl`
D. `(1)/(2)MgL`

Answer

C

Explanation

`U= (1)/(2) Mgl`
`U= (1)/(2)xx` stress `xx` strain `xx` vol''
`=(1)/(2) xx(F)/(A) xx (Delta l)/(l) xx A` & `=(1)/(2) xx Mg xx Delta l`