The Center of Mass of a System of Particles Has

Multiple Choice

The center of mass of a system of particles has a constant velocity if:

A) the forces exerted by the particles on each other sum to zero
B) the external forces acting on particles of the system sum to zero
C) the velocity of the center of mass is initially zero
D) the particles are distributed symmetrically around the center of mass
E) the center of mass is at the geometric center of the system