A wire elongates by 1.0 mm when a load W is hanged from it. If this wire goes over a pulley and two weights W each are hung at the two ends the elongation of the wire will be

Options

A. 1
B. 2 1
C. zero
D. `(1)/(2)`

Answer

A

Explanation

Let us consider the length of wire as L and cross-sectional area A, the material of wire has Young’s modulus as Y.

Then, for `1^(st) "case",Y=(W//A)/(l//L)`
For `2^(nd) "case" , " " Y=(W//A)/(2l'//L)rArrl=(l)/(2)`
So, total elongation of both sides `=2l=1`