Question

A wire is stretched by 8mm when a load of 60N is applied. What will be the extension of a wire of the same material having four times the cross sectional area and twice the original length when one eighth of the load is applied

Answer 1

We have:

$$\frac{Fl}{Ax}=\frac{F(2l)}{8(4A)x'}$$

$$x'=\frac{1}{16}x=\frac{1}{16}8=0.5\ mm$$