Question

Bob P is released from the position of rest at the moment shown. If it collides elastically with an identical bob Q hanging freely then velocity of Q, just after collision is (g = 10 m/s2)

• A. 1 m/s
• B. 4 m/s
• C. 2 m/s
• D. 8 m/s

Answer 1

Answer: (C)

2 m/s

Answer 2

Velocity of P just before collision is = $\sqrt{2gl}$
= 2 m/sec
As collision is elastic and the mass of P and Q is equal therefore just after collision velocity of P is 0 and that of Q is 2 m/sec.

So, The correct answer is (C) : 2 m/sec.