Question

A steel wire of $2mm$ in diameter is stretched by applying a force of $72N$. Stress in the wire is

• A. $2.29\times {10}^{7}N/m^2$
• B.
  $1.17\times {10}^{7}N/m^2$
  
• C.
  $3.6\times {10}^{7}N/m^2$
  
• D.
  $0.8\times {10}^{7}N/m^2$
  

Answer 1

The correct option is A $2.29\times {10}^{7}N/m^2$

Radius $=\frac{2}{2}=1mm$
Stress $=\frac{72}{\pi 1^2\times {10}^{-6}}\frac{N}{m^2}$$=22.9\times {10}^{6}N/m^2$ (using the standard result)