$A$ wire fixed at the upper end stretches by length $l$ by applying a force $F$. The work done in stretching is

The elastic potential energy of a strained body is

When a weight $Mg$ is suspended from a wire of length $L$,the increase in length is $l$ meters. The energy stored in the wire is:

$A$ wire suspended vertically from one of its ends is stretched by attaching a weight of $200\, N$ to the lower end. The weight stretches the wire by $1\, mm$. Then the elastic energy stored in the wire is ........ $J$.

$A$ uniform heavy rod of weight $10 \, N$,cross-sectional area $100 \, \text{cm}^2$ and length $20 \, \text{cm}$ is hanging from a fixed support. The Young's modulus of the material of the rod is $2 \times 10^{11} \, \text{N/m}^2$. Neglecting the lateral contraction,find the elongation of the rod due to its own weight. (In $\times 10^{-10} \, \text{m}$)

The elastic potential energy stored in a copper rod of length $1 \,m$ and area of cross-section $1 \,mm^2$ when stretched by $1 \,mm$ is (Young's modulus of copper $= 1.2 \times 10^{11} \,N/m^2$).