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)

Options

A. l/2
B. l
C. 2l
D. zero

Answer

B

Explanation

Young's modulus of wire in first case.
` Y = (w//A)/(l//L) " "……(i)`
Young 's modulus of wire in second case .
` (w//A)/(l//L) = (w//A)/(2l//L) = 2l =l`