A system of `N` particles is free from any extenal forces.
(a) Which of the following is true for the magnitude of the total momentum of the system?

Options

A. It must be zero
B. It could be non-zero, but it must be constant
C. It could be non-zero, and it might not be constant
D. The answer depends on the nature of the internal forces in the system

Answer

B

Explanation

(a) since momentum is conserved as `F_(ext)=0`
so, if body have some momentum then it will not change it will be constant.
i.e. Momemtum could non-zero but it must be constant internal force have no affect on momentum of body