Question

A copper ball easily slides through a copper ring when it is cold but after there has been heated it does not fit through the ring anymore.

What happens to the ball during heating..?

Answer 1

During heating, the copper ball expands due to an increase in its temperature. This expansion causes its diameter to increase. Therefore, when it cools down, its diameter reduces to its initial size. However, the copper ring also expands when it is heated but not as much as the ball because of its lesser volume. Therefore, when the ball is attempted to pass through the hot ring, the reduced gap between their diameters makes it difficult for the ball to move through. As a result, the ball does not fit through the ring anymore after heating.