A heavy metal ball is suspaended from a staring from the celling of a room. A boy holds the ball in hand and draws it away from its equilibrum position, at some angle with the vertical , very close to his face. The ball is then released from rest. Will it hit back the boy on its return swing? What will be the case if the ball is given some initial push when released?

Explanation

The ball stores some potential energy when it is drawn form its equilibrium postion as the boy does work to lift it. When it is released its potential energy starts converting into kinetic energy and back to potentical energy and so on. But the total energy remains contants (ignoring the air resistance). So, when the ball swings back, it cannot reach beyond the point from where it was released and hence, it cannot hit the boy. But if given some intial push, the boy given the ball some extra kinetic energy. This extra energy makes it swing back farther than from where it started. so, it may hit the boy.