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Question
If the external force acting on a system have zero resultant, the centre of mass
(a) must not move
(b) must not accelerate
(c) may move
(d) may accelerate.
Solution
(b) must not accelerate
(c) may move
If the external force acting on a system has zero resultant,
then, acceleration of centre of mass \[= \frac{\vec{F}_{net}}{M} = 0\]
However, it may move uniformly with constant velocity.
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