Q. A metal rod of Young’s modulus $2\ \times 10^{10}\ Nm^{- 2}\ $undergoes an elastic strain of 0.06%. The energy per unit volume stored in J $m^{- 3}\ is$

A) 3600
B) 7200
C) 10800
D) 14400
Explanation

(a) Energy / volume = $\frac{1}{2}\ \times stress\ \times strain\ $
= $\frac{1}{2}Y \times strain \times strain = \frac{1}{2}Y\ \times strain^{2}$
= $\frac{1}{2} \times 2 \times 10^{10} \times 0.06\ \times 10^{- 2} \times 0.06\ \times 10^{- 2}$
= $3600\ J\ m^{- 3}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.