Q: If the resultant of all the external forces acting on a system of particles is zero, then from an inertial frame, one can surely say that

(a) Linear momentum of the system does not changes in time

(b) Kinetic energy of the system does not change in time

(c) Angular momentum of the system does not change in time

(d) Potential energy of the system does not change in time

Ans: (a)