#### 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 on applying force  F , how much force is needed to stretch wire 2 by the same amount? Option 1) F Option 2) 4F Option 3) 6F Option 4) 9F

As we learnt in

Young Modulus -

Ratio of normal stress to longitudnal strain

it denoted by Y

- wherein

F -  applied force

A -  Area

-  Change in lenght

l - original length

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 1 is A and that of 2 is 3A

v = v1 = v2

or

Because F1 = F2

Correct option is 4.

Option 1)

F

This is an incorrect option.

Option 2)

4F

This is an incorrect option.

Option 3)

6F

This is an incorrect option.

Option 4)

9F

This is the correct option.

## Crack JEE Main with "AI Coach"

• HD Video Lectures
• Unlimited Mock Tests
• Faculty Support

3