Question

A wire of area of cross-section 3.0 mm² and natural length 50 cm is fixed at one end and a mass of 2.1 kg is hung from the other end. Find the elastic potential energy stored in the wire in steady state. 

Young’s modulus of the material of the wire = 1.9 × 10¹¹ N/m² . Take g = 10 m/s ² .

Answer 1

Volume of the wire is

V = (3.0 × 10 ^–6 ) (0.50) = 1.5 × 10 ^–6 m³ 

T = mg

T = (2.1) (10) = 21 N

Stress = T/A

The elastic potential energy of the wire is