Solution

A steel wire of length $2$ metres and cross-sectional area of $2 \times 10^{-4}\,\mathrm{m^{2}}$ is stretched by a force of $400\,\mathrm{N}$. If the Young's modulus of steel is $2 \times 10^{11}\,\mathrm{N/m^{2}}$, calculate the extension of the wire.