Question

A 100 N force stretches the length of a hanging wire by 0.5 mm. The force required to stretch a wire, of the same material and length but having four times the diameter, by 0.5 mm is

• A. 100 N
• B. 400 N
• C. 1200 N
• D. 1600 N

Answer 1

The correct option is D 1600 N

$Y=\frac{FX4X1}{\pi D^2△l}$

In the given problem $F\propto D^2$

Since D is increased by a factor of 4 therefore F is increased by a factor of 16