## In This post you will get answer of Q.

A wire elongates by $l$ mm when a load $W$ is hanged from it. If the wire goes over a pulley and two weights $W$ each are hung at the two ends, the elongation of the wire will be (in mm):

Solution:

## Let us consider the length of wire as L and cross-sectional area A, the material of wire has Youngâ€™s modulus as Y.

Then for 1st case $Y=frac{W/A}{l’/L}$

For 2nd case, $Y=frac{W/A}{2l’/L}$

$therefore l’=l/2$

So, total elongation of both sides $= 2l’= 1$