Sam (68.3 kg) and Alice (41.5 kg) stand on an ice rink, providing them with a nearly frictionless surface to slide on. Sam gives Alice a push, causing her to slide away at a speed (with respect to the rink) of 1.17 m/s.
a) With what speed does Sam recoil?
b) Calculate the change in the kinetic energy of the Sam-Alice system.