Two identical springs of copper and steel are equally strectched. On which more work will have to be done?

Explanation

We know that Young's modulus of steel is more than that of copper. Therefore to stretch them equally more force will be required on the steel spring than that on copper spring. [ `:. F = Ya Delta l//l or F prop Y` for given values of `Delta l, A and l]`
Hence, work done , `W= 1/2 F Delta l, or W prop F`
`( :. Delta I` is constant)
Thus work will have to be done on steel wire that that on copper wire.