A system of particles is free from any external force `vec v and vec a` be the velocity and acceleration of the centre of mass, then it necessarily follows that :

Options

A. `vec v = 0 , vec a = 0`
B. `vec v != 0 , vec a = 0`
C. `vec v = 0 , vec a != 0`
D. None of these

Answer

D

Explanation

(d) Absence of external force, only confirms about the fact that `vec a= 0`. However `vec v` may or may not be zero.