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 $$3$$A. 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?

A
4F
B
9F
C
F
D
6F

Solution

## The correct option is D $$9$$FL, v, same From Hooke’s law $$\displaystyle\frac{F}{A}=4\frac{\Delta l}{L}$$                          $$v_1=v_2$$ $$F=y\frac{A\Delta l}{L}$$                      $$A\times l=3A\times l_1$$ $$\Rightarrow l_1=l_{/3}$$ $$\Rightarrow \displaystyle\frac{F}{F_1}=\frac{\displaystyle\frac{A\Delta l}{l}}{\displaystyle\frac{3A\Delta l}{l_{/3}}}$$ $$\Rightarrow F_1=9F$$ Option (2).Physics

Suggest Corrections

0

Similar questions
View More

People also searched for
View More