Two wires of the same material (Young's modulus $Y$ ) and same length $L$ but radii $R$ and $2R$ respectively are joined end to end and a weight $W$ is suspended from the combination as shown in the figure. The elastic potential energy in the system is
$\frac{{3{W^2}L}}{{4\pi {R^2}Y}}$
$\frac{{3{W^2}L}}{{8\pi {R^2}Y}}$
$\frac{{5{W^2}L}}{{8\pi {R^2}Y}}$
$\frac{{{W^2}L}}{{\pi {R^2}Y}}$
A stretched rubber has
The area of cross-section of a railway track is $0.01\, {m}^{2}$. The temperature variation is $10^{\circ} {C}$. Coefficient of linear expansion of material of track is $10^{-5} /{ }^{\circ} {C}$. The energy stored per meter in the track is ...... ${J} / {m} .$
(Young's modulus of material of track is $10^{11} \,{Nm}^{-2}$ ))
The work done in increasing the length of a metre long wire of cross-sectional area ........ $J.$ $1\,mm^2$ through $1\,mm$ will be $(Y = 2 \times 10^{11}\,Nm^{-2})$
An aluminium rod with Young's modulus $Y =7.0$ $\times 10^{10} N / m ^2$ undergoes elastic strain of $0.04 \%$. The energy per unit volume stored in the rod in SI unit is:
When a $4\, kg$ mass is hung vertically on a light spring that obeys Hooke's law, the spring stretches by $2\, cms$. The work required to be done by an external agent in stretching this spring by $5\, cms$ will be ......... $joule$ $(g = 9.8\,metres/se{c^2})$