Question: Assume that when the brakes are applied a constant frictional force is exerted on the wheels of a car. Which of the following is correct?

Answer Options:
a. The car loses kinetic energy at a constant rate.
b. The distance the car travels before coming to rest is proportional to the speed of the car just before the brakes are applied.
c. The distance the car travels before coming to rest is proportional to the square of the speed of the car just before the brakes are applied.
d. The kinetic energy of the car is inversely proportional to the time, with
𝑡=0t=0 being the instant the brakes are applied.

Answer: c. The distance the car travels before coming to rest is proportional to the square of the speed of the car just before the brakes are applied.

Question: Why does a gyroscope seem to precess only after its rotation slows down?

Answer Options:
a. Gyroscopic precession requires the gyroscope not to move too fast.
b. The gyroscope’s axis of rotation must be somewhat perpendicular to the gravitational field.
c. It takes time for gyroscopic precession to begin.
d. Gyroscopic precession can only happen when energy is lost from the angular motion.

Answer: b. The gyroscope’s axis of rotation must be somewhat perpendicular to the gravitational field.

Question: A roller coaster has eight cars, each of mass of 95.0 kg. The ride begins 47.5 m above the ground. Which of the following is the speed of the train as it encounters a section of track that is 30.0 m below the ride’s starting point? Assume that the train starts from rest.

Answer Options:
a. 24.3 m/s
b. 58.9 m/s
c. 21.7 m/s
d. 8.57 m/s

Answer: a. 24.3 m/s

Question: A steel playground slide is 5.25 m long and is raised 2.75 m on one end. A 45.0 kg child slides down from the top starting at rest. The final speed of the child at the bottom is 6.81 m/s. Find the average force of friction between the child and the slide.

Answer Options:
a. 462 N
b. 242 N
c. 60.6 N
d. 31.7 N

Answer: d. 31.7 N

Question: What would happen to the precession of a gyroscope if it were spinning in the opposite direction?

Answer Options:
a. It would precess in the same direction.
b. It would precess in the opposite direction.
c. It would not precess.
d. It would precess faster.

Answer: b. It would precess in the opposite direction.

Question: Which of the following physical quantities can be negative?

Answer Options:
a. kinetic energy
b. potential energy
c. both kinetic and potential energy

Answer: b. potential energy

Question: What happens to a given mass of water when it is cooled from 8°C to 4°C?

Answer Options:
a. It contracts.
b. It expands.
c. It vaporizes.
d. It does not expand, vaporize, or contract.

Answer: a. It contracts.

Question: A simple pendulum on Earth has a period of 8.0 s. Which of the following is the approximate period of this pendulum on an asteroid where the acceleration due to gravity is roughly 1/16 that of Earth?

Answer Options:
a. 0.5 s
b. 2.0 s
c. 32 s
d. 64 s

Answer: c. 32 s

Question: When a substance goes from a liquid state to a solid state, it ____________.

Answer Options:
a. absorbs heat
b. releases heat
c. neither absorbs nor releases heat

Answer: b. releases heat

Question: The exhaust temperature of a Carnot heat engine is 573 K. What is the intake temperature if the efficiency of the engine is 30%?

Answer Options:
a. 756 K
b. 819 K
c. 711 K
d. 923 K

Answer: b. 819 K