Question

Two wires are made of the same material and have the same volume. However wire 1 has cross-sectional area A and wire 2 has cross-sectional area 3A. If the length of wire 1 increases by Δx on applying force F, how much force is needed to stretch wire 2 by the same amount?

(a) F 

(b) 4F

(c) 6F 

(d) 9F

Answer 1

(d) : For the same material, Young’s modulus is the same and it is given that the volume is the same and the area of cross-section for the wire l₁ is A and that of l₂ is 3A.