1. A sphere of mass 8 kg is moving at 6 m/s to the right until it smacks into a second stationary sphere of mass 5 kg. After the collision, both spheres travel to the right: the first sphere at 1.38 m/s, and the second sphere at 7.38 m/s. What kind of collision took place?
a) This situation is impossible.
b) This is an elastic or nearly elastic collision.
c) This is a perfectly inelastic collision.
d) This is an inelastic (but not perfectly inelastic) collision.
e) More information is needed.
2. Ball A has a mass of 6.0 kg. Ball B has twice the mass of ball A. The two balls collide and stick together in a perfectly inelastic collision. After the collision the combined balls are at rest. If the velocity of ball A before the collision was 9.3 m/s, what was the velocity of ball B before the collision?
a) 4.7 m/s
b) 0.0 m/s
c) -9.3 m/s
d) -4.7 m/s
e) 19 m/s
3. A steel ball traveling at 6 m/s hits a stationary line of three steel balls. Which statement is true if the collision is perfectly elastic?
a) The original ball stops and a single ball moves to the right at 6 m/s.
b) The original ball bounces back at -6 m/s and one ball moves to the right at +6 m/s.
c) All four balls move to the right at 1.5 m/s
d) The original ball stops and the three balls move to the right at 2 m/s.
e) The original ball bounces back at -6 m/s while the other three balls remain stationary.
4. Which of the following equipment is the best choice for investigating elastic or nearly elastic collisions?
a) two sliding carts on a frictionless track that stick together after impact
b) dropping a bowling ball from a balcony so that it makes a dent in the dirt below
c) marble launcher that causes two marbles to collide with each other
d) crash test cars with front ends that crumple upon impact to absorb all the initial kinetic energy
e) a ball of soft clay that flattens when it hits the ground
5. A 2.0 kg ball of clay traveling at 10 m/s collides with a 40 kg ball of clay traveling in the same direction at 2.0 m/s. What is their combined speed if the two balls stick together when they touch?
a) 100 m/s
b) 2.4 m/s
c) 42 m/s
d) 1.0 m/s
e) 3.5 m/s
1. d) This is an inelastic (but not perfectly inelastic) collision.
2. c) -9.3 m/s
3. d) The original ball stops and the three balls move to the right at 2 m/s.
4. c) marble launcher that causes two marbles to collide with each other
5. b) 2.4 m/s