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  4. A non-zero external force acts on a system of particles. The velocity and acceleration of the centre of mass are found to be v0 and a0 at an instant t . It is possible that

Q. A non-zero external force acts on a system of particles. The velocity and acceleration of the centre of mass are found to be and at an instant . It is possible that

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Solution:

If the external force is non-zero then the acceleration of the centre of mass must be non-zero . However, at a particular instant of time velocity of the centre of mass may be zero or non-zero. Hence
From the equation of velocity is in +ve direction and acceleration is in -ve direction, then at some moment velocity will become 0.

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