KEAM 2021 Physics and Chemistry Solved Paper

When a body is strained, work is done against the interatomic forces. This work is stored in the wire in the form of elastic potential energy.
So, stored elastic energy,
U=‌

1

2

Y(‌ strain ‌)2× volume
where, Y is Young's modulus.
∴ Energy stored per unit volume
=‌

1

2

Y(‌ strain ‌)2 ..(i)
We know that, Young's modulus,
∴ Energy stored per unit volume
=‌

1

2

Y(strain)2....(ii)
We know that, Young's modulus,
Y=‌

‌ Stress ‌

‌ Strain ‌

⇒‌‌ Strain =‌

‌ Stress ‌

Y

.....(ii)
Putting Eq. (ii) in Eq (i),
we get Energy stored per unit volume
=‌

1

2

‌

(Stress)2

Y