Question

A metal rod of Young's modulus 2 × 10¹⁰ Nm^–2 undergoes an elastic strain of 0.06%. The energy per unit volume stored in Jm^–3 is –

• A. 3600
• B. 7200
• C. 10800
• D. 14400

Answer 1

Answer: (A)

3600

Answer 2

Energy/Volume = $\frac { 1 } { 2 }$ × stress × strain

= $\frac { 1 } { 2 }$ Y × strain × strain = $\frac { 1 } { 2 }$ Y strain²

= $\frac { 1 } { 2 }$ × 2 × 10¹⁰ × 0.06 × 10^–2 × 0.06 × 10^–2

= 3600 Jm^–3.