Identical springs of steel and copper are equally stretched. On which, more work will have to be done?

Given that Identical Springs Implies that Area of cross-section and Length of both springs are equal. Also Equally Stretched implies that Force is Equal and combining both condition we get that stress are equal in both cases.

We know Work done in stretching is given by

Dividing both sides with will give us

And we know that

Therefore Diving equation RHS with Stress we get,

From Equation 2 we get a relation between work done and young

And we know that Y (steel)>Y (Copper)

Therefore W (Copper)>W (Steel)