Question:
Identical springs of steel and copper are equally stretched. On which, more work will have to be to done?
Solution:
When the identical springs of steel and copper are equally stretched, force is given as:
$W \propto \Delta l$
Because the springs are same, their length and area will also be the same
$\Delta l \propto \frac{l}{Y}$
From both the equations, we can say that
$\frac{W_{\text {steel }}}{W_{\text {copper }}}=\frac{Y_{\text {copper }}}{Y_{\text {steel }}} \Rightarrow W_{\text {steel }}