Question

The bob $A$ of a pendulum released from ${30}^o$ to the vertical hits another bob $B$ of the same mass at rest on a table as shown in fig. How high does the bob $A$ rise after the collision ? Neglect the size of the bobs and assume the collision to be elastic.

Answer 1

The bob A will not rise because when two bodies of same mass undergo an elastic collision, their velocities are interchanged. After collision, ball A will come to rest and the ball B would move with the velocity of A. Thus the bob A will not rise after the collision.