The work done per unit volume to stretch a wire of cross-sectional area $2 \, mm^2$ by $2 \%$ is ....... $MJ/m^3$. Given: Young's modulus $Y = 8 \times 10^{10} \, N/m^2$.

$A$ wire is suspended by one end. At the other end,a weight equivalent to $20 \ N$ force is applied. If the increase in length is $1.0 \ mm$,the increase in energy of the wire will be ....... $J$.

$A$ rubber band catapult has an initial length of $2 \, cm$ and a cross-sectional area of $5 \, mm^2$. It is stretched by an additional $2 \, cm$ and then released to project a stone of mass $20 \, g$. The velocity of the projected stone is (Young's modulus of rubber $= 5 \times 10^8 \, N/m^2$) (in $ \, m/s$)

The work to be done to produce a strain of $10^{-3}$ in a steel wire of mass $2.96 \ kg$ and density $7.4 \ g \ cm^{-3}$ is (Young's modulus of steel $= 2 \times 10^{11} \ Nm^{-2}$)

When a load of $5\,kg$ is hung on a wire, an extension of $3\,m$ takes place. The work done will be ....... $Joule$. (Take $g = 10\,m/s^2$)

Two wires of the same material and length but diameters in the ratio $1:2$ are stretched by the same force. The elastic potential energy per unit volume for the wires,when stretched by the same force,will be in the ratio: (in $:1$)