Section 4.10: Chapter 4 Test
This chapter test evaluates your understanding of Impulse, Momentum, Conservation of Momentum, Elastic and Inelastic Collisions, and Explosions. Work through each problem carefully. You may use a separate sheet of paper for detailed solutions.
Part A: Multiple Choice
1. Which of the following quantities is always conserved in collisions?
A) Kinetic energy
B) Momentum
C) Velocity
D) Impulse
A) Kinetic energy
B) Momentum
C) Velocity
D) Impulse
2. A 0.20 kg ball moving at 5 m/s hits a wall and bounces back at 3 m/s.
What is the impulse on the ball?
A) 0.4 Ns
B) 1.6 Ns
C) –1.6 Ns
D) 0.2 Ns
A) 0.4 Ns
B) 1.6 Ns
C) –1.6 Ns
D) 0.2 Ns
3. In a perfectly inelastic collision:
A) Both momentum and kinetic energy are conserved
B) Momentum is conserved, kinetic energy is not
C) Neither momentum nor kinetic energy is conserved
D) Only kinetic energy is conserved
A) Both momentum and kinetic energy are conserved
B) Momentum is conserved, kinetic energy is not
C) Neither momentum nor kinetic energy is conserved
D) Only kinetic energy is conserved
Part B: Short Answer
4. A 1.0 kg object moving at 6 m/s collides elastically with a 2.0 kg object at rest.
Find the final velocities of both objects.
5. A 3.0 kg cart moving east at 2.0 m/s collides and sticks to a 1.0 kg cart moving west at 1.0 m/s.
Find the velocity of the combined mass after collision.
Part C: Problem Solving
6. A 0.15 kg ball traveling at 20 m/s hits a bat and rebounds in the opposite direction at 30 m/s.
If the contact time is 0.005 s, find the average force exerted on the ball.
7. A 2.0 kg object moving north at 4 m/s explodes into two fragments: one of 1.2 kg moving east at 3 m/s.
Find the velocity of the other fragment.
8. Two ice skaters push off each other. Skater A (50 kg) moves west at 3.0 m/s.
If Skater B has a mass of 70 kg, what is her velocity after the push?