# Energy Practice Quiz

Directions:
Choose the letter of the best answer for each of the questions. When you are finished, click on the button at the bottom of this page that says "Score the Quiz". Good Luck!

1. Which of the following are units of power?
a. N.
b. J.
c. kg.
d. W.

2. All of the following represent energy except
a. W/t
b. Fd
c. mgh
d. 1/2 mv^2

3. If you push an object twice as far while applying the same force you do
a. twice as much work.
b. four times as much work.
c. the same amount of work.

4. A job is done slowly while an identical job is done quickly. Both jobs require the same amount of work, but different amounts of
a. energy.
b. power.
c. both of these.
d. none of these.

5. If you do work on an object in half the time, your power output is
a. half the usual power output.
b. the same power output.
c. twice the usual power output.

6. Exert a force of 5 N for a distance of 4 meters in 2 seconds and you deliver a power of
a. 2.5 W.
b. 10 W.
c. 20 W.
d. 40 W.

7. Exert 100 J in 50 seconds and your power output is
a. 1/4 W.
b. 1/2 W.
c. 2 W.
d. 4 W.
e. more than 4 W.

8. An object is raised above the ground gaining a certain amount of potential energy. If the same object is raised twice as high, it gains
a. four times as much potential energy.
b. twice as much potential energy.
c. the same amount of potential energy.

9. A 1000 kg car and a 2000 kg car are both lifted the same distance in a garage. Lifting up the more massive car requires
a. less work.
b. the same work.
c. twice as much work.
d. four times as much work.

10. An object that has kinetic energy must be
a. moving.
b. up in the air.
c. at rest.
d. attached to a spring.
e. none of these.

11. An object that has potential energy must have this energy because of its
a. speed.
b. momentum.
c. acceleration.
d. position.
e. none of these.

12. Someone can lift containers a height of 1 meter or roll them up a 2 meter long ramp (to the same height.) With the ramp, the force needed is about
a. half as much.
b. the same.
c. twice as much.

13. When a car brakes to a stop, its kinetic energy is changed to
a. stopping energy.
b. potential energy.
c. energy of motion.
d. energy of rest.
e. heat.

14. Which requires more work: lifting a 500 N sack to a height of 2 m or lifting a 250 N sack a hieght of 4 m?
a. lifting the 500 N sack.
b. lifting the 250 N sack.
c. they are the same.

15. A TV is pushed 2 m by a force of 20 N. How much work is done on the TV?
a. 2 J.
b. 10 J.
c. 20 J.
d. 40 J.
e. 80 J.

16. It takes 40 J to push a big box 4 m across the floor. How much force was needed?
a. 4 N.
b. 10 N.
c. 40 N.
d. 160 N.
e. none of these.

17. A 2 kg mass is held 4 m above the ground. How much potential energy does it have?
a. 20 J.
b. 40 J.
c. 60 J.
d. 80 J.
e. none of these.

18. A 2 kg mass has 40 J of potential energy. How far above the ground is it?
a. 1 m.
b. 2 m.
c. 3 m.
d. 4 m.
e. none of these.

19. Using 1000 J of work, a toy elevator is lifted 2 stories in 20 seconds. How much power does the elevator use?
a. 20 W.
b. 50 W.
c. 100 W.
d. 1000 W.
e. 20,000 W.

20. A car moves 4 times faster than an identical car. Compared to the slower car, the faster car has
a. 4 times the KE.
b. 8 times the KE.
c. 12 times the KE.
d. 16 times the KE.

21. The picture below is for questions 21 to 24.
A roller coaster is lifted to the top of the first hill, point A, 100 m high, where it has a total of 15,000 J of energy. It then goes through a frictionless track.

22. If it has 10,000 J of potential energy at point B, how much kinetic energy does it have at point B?
a. 5,000 J.
b. 10,000 J.
c. 15,000 J.
d. 25,000 J.

23. At which point would it have the most total energy?
a. A.
b. B.
c. C.
d. D.
e. E.
f. all the same.

24. At which point would it have the least potential energy?
a. A.
b. B.
c. C.
d. D.
e. E.
f. all the same.

25. At point E, if the coaster has a kinetic energy of 11,000 J, what is its potential energy?
a. 4,000 J.
b. 11,000 J.
c. 15,000 J.
d. 26,000 J.

26. A car moving at 50 km/h will skid to a stop in 20 m. If it is traveling at 150 km/h, how far will it take to skid to a stop?
a. 20 m.
b. 60 m.
c. 90 m.
d. 120 m.
e. none of the above.

27. Which has more kinetic energy: a car moving at 30 km/h or a car with half the mass going at 60 km/h?
a. the 30 km/h car.
b. the 60 km/h car.
c. they have the same kinetic energy.

28. The picture below is for questions 27 and 28.

29. In the picture above, a ball can roll down 3 frictionless ramps as shown. The ball has 5 J of potential energy at the top of the ramps. The ramps are 2, 4 and 6 meters long. If it rolls down the shortest ramp, how much kinetic energy will it have at the bottom of the ramp?
a. 0 J.
b. 2.5 J.
c. 5 J.
d. 10 J.

30. The ball will be going the fastest if it rolls down which ramp?
a. A.
b. B.
c. C.
d. The ball will have the same speed no matter which ramp.

31. You have a mass of 60 kg and run up some stairs that are 5 m high in 6 seconds. (Remember that the acceleration due to gravity is 10 m/s/s.) How much power did you produce?
a. 100 W.
b. 500 W.
c. 720 W.
d. 3600 W.

32. The law of conservation of energy means that
a. energy cannot be created or destroyed.
b. energy can change forms.
c. the total amount of energy cannot change.
d. all of the above.