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 $= 1.2 \times 10^{11} \,N/m^2$).

When the load applied to a wire is increased from $5 \ kg$ wt to $8 \ kg$ wt,the elongation of the wire increases from $1 \ mm$ to $1.8 \ mm$. The work done during the elongation of the wire is (Acceleration due to gravity $= 10 \ m/s^2$)

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 ratio of the increase in energy of the wire to the decrease in gravitational potential energy when the load moves downwards by $1\, mm$ will be:

$A$ 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$)

$A$ wire suspended vertically from one end is stretched by attaching a weight $200 \,N$ to the lower end. The weight stretches the wire by $1 \,mm$. The elastic potential energy gained by the wire is ....... $J$