Mechanics: Center of Mass.
A 60 kg woman and a 90 kg man stand 10.0 m apart on frictionless ice.
(a) If they hold on to the two ends of a rope, and the man pulls on the rope so that he moves 2.5 m, how far from the woman will he be now? in meters
(b) How far will the man have moved when he collides with the woman? in meters