Question

It is easier to catch a table tennis ball than a cricket ball, even when both are moving with the same velocity. Why?
(A) Table tennis ball is very small
(B) Table tennis ball has more electromagnetic force
(C) The ball is special
(D) No reason

Answer 1

Hint: The effort required to stop any moving object depends on the force the object exerts on the stopping body when it is brought to rest. In the given question, we are talking about catching a ball, so the force will be exerted on the hand of the catcher. So if we can find whether the table tennis ball exerts more force on the hand of the catcher or the cricket ball, we can easily deduce which ball would be easier to catch and why.

Complete step by step answer:
From Newton’s second law of motion, we know that the force exerted by any moving body can be given as the rate of change of its linear momentum.
You must be aware of the momentum of a body. It is defined as the product of the mass and the velocity of any moving object. In the question, we have been told that both the balls travel with the same velocity. Hence we can say that the momentum will now depend solely on the mass of the balls. It is common sense that a table tennis ball has much less mass as compared to a cricket ball.
When the balls are caught and brought to rest, higher their travelling momentum, greater would be the change in their momentum as the final momentum of both balls will be zero at rest, after being caught.
From the above discussion, we can say that the force the table tennis ball will exert upon being caught will be less than the force the cricket ball and therefore the table tennis ball will be easier to catch than the cricket ball.
Upon analysis of the options, we don’t find any option regarding the mass of the balls but there is one option that says the tennis ball is very small, which is a casual reference to a lesser mass.

Hence option (A) is the correct answer to the given question.

Note:
Students can choose the correct option by careful and reasonable elimination, for example, there must be some reason for the phenomenon in the question and hence, option (D) is wrong. Similarly, option (C) also does not make any sense as physics does not depend on the speciality of balls. In option (B) there is a mention of the electromagnetic force, but for that, the body would have to be charged. Hence all the options other than option (A) can be easily eliminated.