A load of 4 kg is suspended from a ceiling through a steel wire of length 2 m and radius 2 mm. It is found that, the length of the wire increases by 0.031 mm as equilibrium is achieved. What would be the Young's modulus of steel? (Take, g = 3.lπ ms-2)

Given, mass of load = 4 kgLength of wire, l = 2 mRadius of wire (cross-section) = 2 mm = 2×10−3mand change in length,  Δl=0.031mm=0.031×10−3mYoung's modulus,Y= Stress  Strain =mgAΔll=4×3.1ππ2×10−32(Δl/l)⇒ Y=4×3.1ππ×4×10−6×20.031×10−3=3.1×20.031×109=2×1011Nm−2