Question

A copper wire of $1mm$ diameter is stretched by applying a force on $10N$. Find the stress in the wire.

• A. $1.273\times {10}^{7}N/m^2$
• B. $1.373\times {10}^{7}N/m^2$
• C. $1.473\times {10}^{7}N/m^2$
• D. $1.573\times {10}^{7}N/m^2$

Answer 1

The correct option is A $1.273\times {10}^{7}N/m^2$

$\begin{array}{c}\text{given diameter = 1mm}\\ \begin{array}{cc}\Rightarrow \text{radius of wire}& =0.5\times {10}^{-3}m\\ & =5\times {10}^{-4}m\end{array}\end{array}$

$\begin{array}{c}\text{Force applied}=10N\\ \therefore \text{Stress}=\frac{10}{\pi \times 25\times {10}^{-8}}\\ =0.1273\times {10}^8\\ \text{Stress}=1.273\times {10}^{7}N/m^2\end{array}$