Question

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) -

• A. $l$
• B. $2l$
• C. zero
• D. $\frac{l}{2}$

Answer 1

The correct option is A $l$

$\begin{array}{c}\text{Hence at equilibriun}\\ \begin{array}{c}T=W\\ \frac{W}{A}=Y\frac{l_1}{L}\\ \Rightarrow l_1=\frac{WL}{AY}\end{array}\end{array}$

$\begin{array}{c}\text{At equilibnumu}T=W\text{for each}\\ \text{side of wire}\to \\ \frac{W}{A}=Y\frac{l_2}{L}\\ \Rightarrow l_2=\frac{WL}{AY}\end{array}$

$\text{hence elongation will be same}\Rightarrow \text{ans}\to \left(A\right)$