Question

A wire of length L and radius r is fixed at one end and force F applied to the other end produces an extension Y. The extension produced in another wire of the same material of length 2L and radius 2r by a force of 2F is –

• A. Y
• B. 2 Y
• C. Y/2
• D. 4/ Y

Answer 1

Answer: (A)

Y

Answer 2

Dl = $\frac{F\mathcal{l}}{(\pi r^{2})Y}$ = y

Dl' = $\frac{(2F)(2\mathcal{l)}}{\pi(2r)^{2} \times Y}$ = $\frac{F\mathcal{l}}{\pi r^{2}Y}$ = y