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

Options

A. linear momentum of the system does not change in time
B. kinetic energy of the system changes in time
C. angular momentum of the system does not change in time
D. potential energy of the system does not change in time

Answer

A, B

Explanation

As external force is zero. `P` is constant but `K.E.` increases. Due to external torque, angular momentum changes. `P.E.` also changes.