MCAS Conservation of Energy and Momentum 1

1.

1 point

A book weighing 18.0 N is lifted from the floor and placed on a shelf 1.5 m high. What is the minimum amount of work required to accomplish this task?

12J

27J

120J

270J

2.

1 point

Neglecting air resistance, which of the following statements describes the change in energy of a diver who falls downward toward a swimming pool?

Potential energy increases, kinetic energy increases, and total energy increases.

Potential energy decreases, kinetic energy decreases, and total energy decreases.

Potential energy decreases, kinetic energy increases, and total energy remains the same.

Potential energy increases, kinetic energy decreases, and total energy remains the same.

3.

1 point

The power supplied to a light bulb is 100 W. How much electrical energy is used by this light bulb in 20 s?

5J

100J

500J

2000J

4.

1 point

What is the magnitude of the momentum of a 0.15 kg baseball moving at 25 m/s?

3.8 kg • m/s

47 kg • m/s

167 kg • m/s

1110 kg • m/s

5.

1 point

A 4000 kg truck is moving north at 8 m/s, and a 1200 kg car is moving north at 30 m/s. Which of the following statements best compares the truck and the car?

The truck has less inertia than the car.

The truck has less momentum than the car.

The truck has more mass but less weight than the car.

The truck has more kinetic energy but less potential energy than the car.

6.

1 point

The diagram below shows a section of a roller coaster track. Five points on the track are labeled.

Between which two points will the roller coaster’s gravitational potential energy be converted into kinetic energy?

T and U

U and V

V and W

W and X

7.

1 point

What is the magnitude of the momentum of a 0.50 kg ball moving in a straight line at 5.0 m/s?

0.1 kg • m/s

2.5 kg • m/s

6.3 kg • m/s

10 kg • m/s

8.

1 point

An electric fan has a power output of 60 W. How much work is done if the fan operates for 120 s?

0.5 J

60J

120J

7200J

9.

1 point

An athlete is training for a race by performing timed trials of sprints up a staircase. Which set of variables most directly affects the athlete’s power?

body weight, height climbed, width of steps

body weight, time spent climbing, width of steps

height climbed, time spent climbing, body weight

height climbed, time spent climbing, width of steps

10.

1 point

The potential energy of a 77 kg diver standing on a 20 m high diving tower is 15,400 J. Two-thirds of the way down during the dive into the pool, his potential energy is 5,100 J.
Neglecting air resistance, what is the diver’s kinetic energy at this point?

2,550 J

7,650 J

10,300 J

12,850 J

11.

1 point

Which of the following has the greatest momentum?

0.2 kg ball moving at 40 m/s

500 kg car traveling at 16 m/s

2000 kg truck traveling at 9 m/s

50 kg child skateboarding at 4 m/s

12.

1 point

Work is performed on an object by raising it 2 m above the floor. Which of the following types of energy must change in this situation?

chemical energy

magnetic energy

mechanical energy

thermal energy

13.

1 point

An inventor claims to have designed a perpetual motion machine, a device that creates its own power. Which of the following laws best explains why a perpetual motion machine cannot work?

law of conservation of energy

law of conservation of matter

Newton’s second law

Newton’s third law

14.

1 point

A hand-held video game is powered by batteries. After playing the game for several minutes, a student notices that the game feels warm.
Which of the following is the most likely explanation for this observation?

The game creates energy when it is turned on.

Some of the energy from the batteries is changed to heat.

Some of the energy from the batteries is changed to friction.

The game receives heat energy from the person playing it.

15.

1 point

An object with a mass of 3 kg has a momentum of 75 kg • m/s. What is its velocity?

0.4 m/s

7.1 m/s

25 m/s

72 m/s

16.

1 point

A 1000 kg automobile is traveling at an initial speed of 20 m/s. It is brought to a complete stop in 5 s over a distance of 50 m.
What is the work done in stopping the automobile?

10,000J

40,000J

50,000J

200,000J

17.

1 point

The table below provides information about the daily use of some typical appliances.

Which appliance uses the most energy?

dishwasher

air conditioner

laptop computer

clock radio

18.

1 point

While playing a game at a fair, a person lifts a mallet above her head. She then lets the mallet fall toward a target, as shown below.

Which of the following statements describes an energy change that takes place as the person lifts the mallet and then lets it fall toward the target?

Kinetic energy increases as the mallet reaches its highest point.

Potential energy decreases as the mallet reaches its highest point.

Kinetic energy converts to potential energy as the mallet falls toward the target.

Potential energy converts to kinetic energy as the mallet falls toward the target.

19.

1 point

A 20 kg child is traveling 3 m/s on an amusement park ride. What is the magnitude of the child’s momentum?

6.7 kg • m/s

60 kg • m/s

90 kg • m/s

200 kg • m/s

20.

1 point

If 10^5 J of energy is used in 10^3 s, what is the average power consumption in watts?

10^2 W

10^8 W

10^11 W

10^15 W

21.

1 point

A pendulum swings back and forth several times, as shown in the diagram below. Assume friction is negligible.

Which of the following graphs best illustrates the potential energy (PE) and the kinetic energy (KE) of the pendulum over a period of several swings?