A copper wire of diameter 2 mm is 10 m long and stretched out between two posts.

Question:

A copper wire of diameter 2 mm is 10 m long and stretched out between two posts. The normal stress (pressure) σ = E (L – Lo)/Lo, depends on the length L versus the unstretched length Lo and Young’s modulus E = 1.1 × 106 kPa. The force is F = Aσ and measured to be 110 N. How much longer is the wire and how much work was put in?