Question

If to break a wire of one metre length, minimum $40$ kg-wt is required, then the break a wire of same material $6m$ in length and double in radius, the breaking weight required will be

• A. $40kg-wt$
• B. $80kg-wt$
• C. $160kg-wt$
• D. $320kg-wt$

Answer 1

The correct option is C $160kg-wt$

Breaking force $=$ Breaking stress $\times$ ares of cross-section of wire
$\therefore$ Breaking force $\propto r^2$
If radius becomes doubled, then breaking force becomes $4$ times
i.e., $40\times 4=160kg-wt$.