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Name: ____________________________________
Chapter 3 Test: Safety
Period _____
Burns
Date: __________
CP Physics
Multiple Choice
Identify the choice that best completes the statement or answers the question.
1. Which of the following has the greatest inertia?
a. a tortoise with a mass of 275 kg moving at a velocity of 0.55 m/s
b. a hare with a mass of 2.7 kg moving at a velocity of 7.5 m/s
c. a turtle with a mass of 91 kg moving at a velocity of 1.4 m/s
d. a roadrunner with a mass of 21.8 kg moving at a velocity of 7 m/s
2. Which of the following has the greatest momentum?
a. a tortoise with a mass of 275 kg moving at a velocity of 0.55 m/s
b. a hare with a mass of 2.7 kg moving at a velocity of 7.5 m/s
c. a turtle with a mass of 91 kg moving at a velocity of 1.4 m/s
d. a roadrunner with a mass of 21.8 kg moving at a velocity of 7 m/s
3. A rubber ball moving at a speed of 5 m/s hit a flat wall and returned to the thrower at 5 m/s. The
magnitude of the momentum of the rubber ball
a. increased.
b. remained the same.
c. decreased.
d. was not conserved.
4. The impulse experienced by a body is equivalent to the body’s change in
a. velocity.
b. momentum.
c. kinetic energy.
d. force.
5. In a two-body collision,
a. momentum is always conserved.
b. kinetic energy is always conserved.
c. neither momentum nor kinetic energy is conserved.
d. both momentum and kinetic energy are always conserved.
6. Two balls of dough collide and stick together. Identify the type of collision.
a. elastic
b. inelastic
c. nearly elastic
d. perfectly inelastic
7. A billiard ball collides with a second identical ball in an elastic head-on collision. What is the kinetic
energy of the system after the collision compared with the kinetic energy before the collision?
a. unchanged
b. two times as great
c. one-fourth as great
d. four times as great
Use the following to answer questions #8 – 10: A small VW Beetle is in a collision with a giant truck.
8.
Which vehicle delivers a bigger force?
a. The truck’s force is bigger than the Beetle’s.
b. The truck’s force is smaller than the Beetle’s.
c. Neither, the forces are equal but opposite.
d. Can’t tell without more information.
9. Which vehicle received the bigger impulse?
a. The truck’s impulse is bigger than the Beetle’s.
b. The truck’s impulse is smaller than the Beetle’s.
c. Neither, the impulses are equal but opposite.
d. Can’t tell without more information.
10. Which vehicle had the bigger change in momentum?
a. The truck’s change in momentum is bigger than the Beetle’s.
b. The truck’s change in momentum is smaller than the Beetle’s.
c. Neither, the changes in momentum are equal but opposite.
d. Can’t tell without more information.
11. A dull knife does not cut as well as a sharp knife when pushed equally hard. A sharp knife cuts better
because it
a. Exerts greater pressure
b. Requires more momentum
c. Has a longer edge
d. Has more inertia
12. When two identical eggs dropped from equal heights, When landing on two different surfaces, Egg A
breaks and Egg B does not. You may conclude that Egg B
a. Had less kinetic energy
b. Had a smaller force acting on it.
c. Had less work done on it
d. Had less momentum
13. A car moving at 5 m/s brakes to a stop at a distance of 2 m. What distance would be required by the
same braking force to stop the car at a speed of 10 m/s?
a. 4 m
b. 8 m
c. 16 m
d. 32 m
14. Which best describes a car moving at constant speed?
a. There is a constant unbalanced force pushing it forward.
b. There are no forces acting on the car.
c. There is an increasing force on the car that pushes it forward.
d. All of the forces acting on the car sum up to zero.
15. Which type of seat belt would be more safe to have in your car?
a. A wide seat belt that stretches slightly.
b. A narrow seat belt that stretches slightly.
c. A wide seat belt that does not stretch at all.
d. A narrow seat belt that does not stretch at all.
Problem Solving: Be sure to show all work in order to receive all credit. This means: a labeled diagram,
equation(s) used, and numbers plugged in, in addition to the correct answer with correct units.
1. A car has a momentum of 52,500 kgm/s while in motion, and has a mass of 1,750 kg. What is the
velocity of the car?
2. A white Cue Ball has a mass of 0.26 kg, and the Eight Ball has a mass of 0.15 kg. The Cue Ball comes
in with a velocity of 1.5 m/s to the right and the Eight Ball is at rest. After the collision, the Cue Ball
continues forward with a velocity of 0.40 m/s.
a. What is the velocity of the Eight Ball after the collision?
b. Is this an elastic or inelastic collision? Prove it!
3. A bullet with a mass of 0.015 kg has a velocity of 270 m/s. It strikes a concrete block with a mass of 7.5
kg which is initially at rest and get stuck inside the concrete.
a. What is the final velocity of the bullet and concrete?
b. How much kinetic energy is lost during the collision?
4. A rocket with a mass of 32,800 kg experiences a net force of 800,000 N when the engines are switched
on. During one take-off, they are turned on exactly for 2 minutes.
a. What is the change in momentum of the rocket?
b. If the rocket starts at rest, what is the final velocity during the engine burn?
c. If, as stated above, the rocket experiences a net force of 800,000 N, what is the force of the
engines on the rocket? (Hint: Draw a FBD!)
5. A 2.0 kg mass is dropped from 0.30 m into a sandbox. It leaves an indentation that is 0.04 m deep.
a. How fast was the mass moving when it hit the sand?
b. What is the force required to bring the mass to rest?
c. What is the impulse delivered to the mass by the sand?
Extra Credit:
An 82 kg man drops from rest on a diving board 3 m above the surface of the water and comes to rest 0.55 s
after piercing the water. What force does the water exert upwards on him? (Hint: draw out a picture of this
situation)