Question

To break a wire of 1 mm radius a force of 10 N is required. Find the force required to break a wire of 3mm radius.

Answer 1

We know that, the required force depends upon the cross-sectional area.
$F=Stress\times Area$
So, $\frac{F_1}{F_2}=\frac{R_1^2}{R_2^2}$
$\Rightarrow F_2=\frac{3^2}{1^2}\times 10$ $=90N$