Question:
A steel wire having a radius of $2.0 \mathrm{~mm}$, carrying a load of $4 \mathrm{~kg}$, is hanging from a ceiling. Given that $\mathrm{g}=3.1 \pi \mathrm{ms}^{-2}$, what will be the tensile stress that would be developed in the wire?
Correct Option: , 3
Solution:
(3) Given,
Radius of wire, $r=2 \mathrm{~mm}$
Mass of the load $m=4 \mathrm{~kg}$
Stress $=\frac{F}{A}=\frac{m g}{\pi(r)^{2}}$
$=\frac{4 \times 3.1 \pi}{\pi \times\left(2 \times 10^{-3}\right)^{2}}=3.1 \times 10^{6} \mathrm{~N} / \mathrm{m}^{2}$