Question

A wire of length L and radius r is clamped rigidly at one end. When the other end of the wire is pulled by a force f, its length increases by l. Another wire of the same material of length 2L and radius 2r, is pulled by a force 2f. Find the increase in length of this wire.

Answer 1

Let Y be the Young’s modulus of the material. Then

Let the increase in length of the second wire be l'. Then