Elasticity

A 4 kg stone attached at the end of a steel wire is being whirled at a constant speed $12 \mathrm{~ms}^{-1}$ in a horizontal circle. The wire is 4 m long with a diameter 2.0 mm and Young's modulus of the steel is $2 \times 10^{11} \mathrm{Nm}^{-2}$. The strain in the wire is.