Two wires are made of the same material and have the same volume. The area of cross sections of the first and the second wires are A and 2A respectively. If the length of the first wire is increased by `Delta l` on applying a force F, how much force is needed to stretch the second wire by the same amount ?

Options

A. 2
B. 4
C. 8
D. 16

Answer

B

Explanation

Since the two wires have same volume
Length of wire 1 = l, Area of wire 1 = A
Length of wire 2 = `l/2`, Area of wire `2 = 2A`
Wire 1 : `Y_1 = (F/A)/((Deltal)/(l)) " " Y_1 = Y_2" Wire" 2 : Y_2 = ((F.)/(A))/((Deltal)/((l//2)))`
`F/A xx l/(Delta l) = (F.)/(2A) xx l/(2Delta l)`
`F = (F.)/4 implies F. = 4F`.