A uniform linearly elastic wire of length L, area A and Young's modulus Y is stretched gradually from zero force to a final tensile force F. Which statements are correct?
Select all that apply

Question

A uniform linearly elastic wire of length L, area A and Young's modulus Y is stretched gradually from zero force to a final tensile force F. Which statements are correct?

G1 Physics · Accepted Answer

For gradual linear loading, force rises linearly from zero to F while extension rises from zero to ΔL. Hence, U = average force × extension = ½FΔL. Using ΔL = FL/[AY], we get U = F²L/[2AY]. Per unit volume, u = U/(AL) = ½σε. The same quantity equals the area under the stress-strain curve up to the working strain. Therefore all four statements are correct.