Consider two skaters, Jack (80 kg) and Jill (40 kg), who can move along a straight line (X-axis). Initially, the skaters are at rest and holding hands and their Xem is 0. Later, Jill pushes Jack away to the left. Assume there is no friction. When Jack reaches X=-4.0 m, his velocity is -2.0 m/s, (a) what is Jill's X coordinate? (b) what is Jill's velocity? (c). what is the horizontal velocity of the center of mass of the skaters?