A washing machine spin dries clothes. It starts spinning at 20 rad/s and slows down to 8 rad/s while turning through 500 revolutions. a. What is the angular acceleration?
b. How much time does it take to slow down?

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.