The work-energy theorem states that a force acting on a particle as it moves over a changes the energy of the particle if the force has a component parallel to the motion. The work-energy theorem states that a force acting on a particle as it moves over a changes the energy of the particle if the force has a component parallel to the motion.

In a game of pool, ball a is moving with a velocity v0 of magnitude v0 = 15 ft/s when it strikes balls b and c, which are at rest and aligned as shown. knowing that after the collision the three balls move in the directions indicated and assuming frictionless surfaces and perfectly elastic impact (that is, conservation of energy), determine the magnitudes of the velocities va, vb, and vc.