(D) It quadruples.
(E) It doubles.
3 . Two balls, of mass m and 2m , collide and stick together. The combined balls are at rest after the
collision. If the ball of mass m was moving 5 m/s to the right before the collision, what was the
velocity of the ball of mass 2m before the collision?
(A) 2.5 m/s to the right
(B) 2.5 m/s to the left
(C) 10 m/s to the right
(D) 10 m/s to the left
(E) 1.7 m/s to the left
4 . Two identical balls have initial velocities v 1 = 4 m/s to the right and v 2 = 3 m/s to the left,
respectively. The balls collide head-on and stick together. What is the velocity of the combined balls
after the collision?
(A) m/s to the right
(B) m/s to the right
(C) ½ m/s to the right
(D) m/s to the right
(E) 1 m/s to the right
Free Response:
5 . A 75-kg skier skis down a hill. The skier collides with a 40-kg child who is at rest on the flat surface
near the base of the hill, 100 m from the skier’s starting point, as shown above. The skier and the child
become entangled. Assume all surfaces are frictionless.
(a) How fast will the skier be moving when he reaches the bottom of the hill? Assume the skier is at
rest when he begins his descent.
