Question

How much force acts on body whose momentum is not constant ?

Answer 1

$\huge\bold\green{AnSwEr:-}$

In a closed system, the total momentum never changes. Note that there absolutely can be external forces acting on the system; but for the system's momentum to remain constant, these external forces have to cancel, so that the net external force is zero......♥

Answer 2

In a closed system, the total momentum never changes. Note that there absolutely can be external forces acting on the system; but for the system's momentum to remain constant, these external forces have to cancel, so that the net external force is zero........!