Many cars are filled with an air bag. In a collision, the air bag inflates and reduces the effect of the impact between the passenger and the dashboard. In a test of the air bag, a heavy ball is used instead of the passenger. The car is travelling at 14m/s when it hits a wall. The air bag inflates and the ball takes 3.0 s to come to rest. Calculate the average deceleration of the ball.

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.