MCQ
A man inside a freely falling box throws a heavy ball towards a side wall. The ball keeps on bouncing between the opposite walls of the box. We neglect air resistance and friction. Which of the following figures depicts the motion of the centre of mass of the entire system (man, the ball and the box)?

  • B

  • C

  • D

Answer

Correct option: A.

a
(a)

As centre of mass is subjected to a downward external force only, so its motion is along the direction of external force, i.e. downwards. Any internal force does not change position of centre of mass.

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