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)

Question

Dr. Abubacker · Accepted Answer

(a) Let us consider the length of wire as L and cross-sectional area A, the material of wire has Young’s modulus as Y.
[image:9_image12.jpeg]
Then for 1st case $Y = \frac{W/A}{l/L}$
For 2 $^{nd}$ case, $Y = \frac{\frac{W}{A}}{\frac{2l^{'}}{L}}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ $
$	herefore\ \ l^{'} = \frac{l}{2}$
So, total elongation of both sides $= 2l^{'} = l$

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)

Explanation

Reviewed by Dr. Abubacker

Want more practice?