A block of mass $M$ is suspended from a wire of length $L$, area of cross-section $A$ and Young's modulus $Y$. The elastic potential energy stored in the wire is

$K$ is the force constant of a spring. The work done in increasing its extension from ${l_1}$ to ${l_2}$ will be

The work done per unit volume to stretch the length of area of cross-section $2 \,mm ^2$ by $2 \%$ will be ……. $MJ / m ^3$ $\left[Y=8 \times 10^{10} \,N / m ^2\right]$

A brass rod of cross-sectional area $1\,c{m^2}$ and length $0.2\, m$ is compressed lengthwise by a weight of $5\, kg$. If Young's modulus of elasticity of brass is $1 \times {10^{11}}\,N/{m^2}$ and $g = 10\,m/{\sec ^2}$, then increase in the energy of the rod will be

Weight is suspended to the end of elastic spring its increased length depends upon what ?