Question

A system of particles is free from any external force. If $\overrightarrow{v}$ and $\overrightarrow{a}$ be the velocity and acceleration of the centre of mass, then it necessarily follows that

• A. $\overrightarrow{v}=0;\overrightarrow{a}=0$
• B. $\overrightarrow{v}\ne 0;\overrightarrow{a}=0$
• C. $\overrightarrow{v}=0;\overrightarrow{a}\ne 0$
• D. Both (a) and (b)

Answer 1

The correct option is D Both (a) and (b)

Absence of external force, only confirm about the fact that $\overrightarrow{a}=0$. However, $\overrightarrow{v}$ may or may not be zero