An Axial Pull of 50 KN Is Suddenly Applied to a Steel

An axial pull of 50 KN is suddenly applied to a steel bar 2 m long and 1000 mm² in cross-section. If modulus of elasticity is 200 GPa, find strain energy stored in the bar

A) 10,000 N.mm
B) 20,000 N.mm
C) 25,000 N.mm
D) 50,000 N.mm