SOLUTION: Particle A of mass 2.0kg is moving at 15m/s to the east. Particle B of mass 3.0kg is moving to the west at 10.0m/s. Find the velocity of the center of the mass of the two particles

Consider number line west-east and place the origin at the starting point.


In time t, particle A has the coordinate 15t meters, moving east.


In time t, particle B has the coordinate -10t meters, moving west.


The center of mass has the coordinate   =  = 0.


We see that the center of mass has the constant coordinate 0 (meters), so the center of coordinate is not moving: it is at rest.


ANSWER.  The velocity of the center of masses is 0 (zero, ZERO).