Question

To break a wire of 1 m length, minimum 40 kg weight is required. Then the wire of the same material of double radius and 6 m length will require breaking weight

• A. 80 kg weight
• B. 240 kg weight
• C. 200 kg weight
• D. 160 kg weight

Answer 1

The correct option is D 160 kg weight

$\begin{array}{c}\text{Breaking stress is constant for the wire}\\ \text{Stress}=\frac{F}{A}\\ \begin{array}{cc}\frac{F_1}{A_1}=\frac{F_2}{A_2}\Rightarrow F_2& =F_1\left(\frac{A_2}{A_1}\right)\\ & =40\left(\frac{\pi (2r{)}^2}{r^2}\right)\\ F_2& =160kg-wt\end{array}\end{array}$