Question

The bob A of a simple pendulum is released when the string makes an angle of 45° with the vertical. It hits another bob B of the same material and same mass kept at rest on the table. If the collision is elastic
(a) both A and B rise to the same height
(b) both A and B come to rest at B
(c) both A and B move with the velocity of A
(d) A comes to rest and B moves with the velocity of A

Answer 1

I think c is correct option

Answer 2

Answer:

D) A comes to rest and B moves with the velocity of A

Explanation:

In a perfectly elastic head on collision, when two equal masses collide with each other, then they exchange their speeds.  In the given figure, bob A is moving with certain speed and bob B is at rest.

Thus, after the collision, bob A will come to rest and bob B will start moving with the speed of the bob A. The bob A will transfer whole of its momentum to bob B and so, bob A, will not rise at all after the collision. The Bob will not rise because when two bodies of same mass undergo an elastic collision, there velocities are interchanged and Ball A rests and Ball B moves. Due to the same mass of A and B and also due to the elastic collision, the velocities of spheres get interchanged after collision.