Question

Two wires are made of the same material and have the same volume. The first wire has cross-sectional area A and the second wire has cross-sectional area 3A. If the length of the first wire is increased by Δx on applying a force F, how much forcce is needed to stretch the second wire by the same amount ?

Answer 1

Since the two wires have same volume.

Length of wire 1 =l=l

Length of wire 2 =l3=l3

Area of wire 1 =A=A

Area of wire 2 =3A=3A

wire 1:

Y=F/AΔx/lY=F/AΔx/l---------(1)

wire 2:

Y=F′/AΔx/l/3Y=F′/AΔx/l/3-------------(2)

from (1) and (2)

FA×lΔx=F13A×l3ΔxFA×lΔx=F13A×l3Δx

F1=9FF1=9F

Hence c is the correct answer.

Answer 2

Answer:

9F

Explanation:

Hope this helps you