Question

If the stress is S and the Young’s modulus is Y of material of a wire, the energy stored in the wire per unit volume is?

(a) 2Y/S

(b) S/2Y

(c) 2S^2 Y

(d) S^2/ 2Y

I had been asked this question by my school teacher while I was bunking the class.

Enquiry is from Stress and Strain topic in chapter Thermal Properties of Matter of Engineering Physics I

Answer 1

The correct choice is (d) S^2/ 2Y

To elaborate: Elastic potential energy stored per unit volume,

u=1/2×Stress×Strain=1/2×Stress×Stress/Y=S^2/2Y.