Name:    Quiz: Energy

Multiple Choice
Identify the choice that best completes the statement or answers the question.

1

An arrow in a bow has 90 J of potential energy. Assuming no loss of energy to heat, how much kinetic energy will it have after it has been shot?
 a. 180 J b. 45 J c. 70 J d. 0 J e. 90 J

2

The unit of power is the
 a. meter. b. watt. c. newton. d. second. e. joule.

3

If Nellie Newton pushes an object with twice the force for twice the distance, she does
 a. twice the work. b. eight times the work. c. the same work. d. four times the work.

4

A ball is thrown into the air with 120 J of kinetic energy, which is transformed to gravitational potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, its kinetic energy is
 a. less than 120 J. b. more than 120 J. c. 120 J. d. Not enough information given.

5

Energy is changed from one form to another with no net loss or gain.
 a. Sometimes true b. Always true c. Always false

6

A 90-N object moves at 1 m/s. Its kinetic energy is
 a. 90 J. b. 1 J. c. more than 90 J. d. 4.5 J.

7

The units for energy are
 a. joules b. watts c. newtons d. meters

8

An object that has kinetic energy must be
 a. elevated. b. moving. c. at rest. d. falling.

9

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

10

A heavy object and a light object are released from rest at the same height and time in a vacuum. As they fall, they have equal
 a. energies. b. momenta. c. weights. d. all of the above e. none of the above

11

A 4.0-kilogram mass is moving with a speed of 2.0m/s.   What is the kinetic energy of the mass?
 a. 6.0 J b. 16.0 J c. 8.0 J d. 4.0 J

12

If the velocity of a moving object doubles, then what else doubles?
 a. acceleration. b. kinetic energy. c. momentum. d. all of the above e. none of the above

13

How many joules of work are done on a box when a force of 45 N pushes it 7 m?
 a. 315 J b. 7 J c. 45 J d. 6 J e. 1 J

14

An object at rest may have
 a. velocity. b. speed. c. momentum. d. energy. e. none of the above

15

How much work is done on a 70-N object that you lift 6 m?
 a. 1 J b. 70 J c. 420 J d. 0 J e. 6 J

16

The ratio of output force to input force of a simple machine is called the
 a. efficiency. b. pivot point. c. lever arm. d. fulcrum. e. mechanical advantage.

17

Three objects move with a velocity of 3 m/s.

What is the total kinetic energy of the system?
 a. 20 J b. 1 J c. 45 J d. 30 J

18

The unit of work is the
 a. second. b. meter. c. watt. d. joule. e. newton.

19

Potential energy is the energy an object has because of its
 a. speed. b. density. c. location. d. size. e. temperature.

20

When a car’s speed triples, its kinetic energy
 a. triples. b. increases by nine times. c. remains the same. d. increases by four times. e. none of the above

21

A 4.0-kg concrete block falls to the ground from a 3-m-high roof. What is the approximate kinetic energy of the concrete block just before it touches the ground?
 a. 120J b. 24J c. 40J d. 12J

22

The amount of potential energy possessed by an elevated object is equal to
 a. the distance it is lifted. b. the power used to lift it. c. the value of the acceleration due to gravity. d. the work done in lifting it. e. the force needed to lift it.

23

In physics, work is defined as
 a. force divided by time. b. force times distance. c. distance divided by time. d. force times time. e. force divided by distance.

24

Power is defined as the
 a. distance divided by the time taken to move that distance. b. force on an object times the distance the object moves. c. force on an object divided by the time the force acts. d. work done times the time taken to do that work. e. work done on an object divided by the time taken to do the work.

25

How much power is expended if you lift a 40 N crate 8 meters in 1 second?
 a. 8 W b. 320 W c. 5 W d. 0 W e. 40 W

26

A hydraulic lift used at an automotive repair shop raises a 1500-kilogram car one meters off of the ground. What is the potential energy given to the car?
 a. 15,000 J b. 1500 J c. 7,500 J d. 750 J

27

As an object falls, its potential energy
 a. increases b. stays constant c. cannot be determined d. decreases

28

Which requires more work: lifting a 50-kg sack vertically 4 meters or lifting a 25-kg sack vertically 8 meters?
 a. Lifting the 50 kg sack b. Lifting the 25 kg sack c. Both require the same amount of work.

29

How much work is done on a 10-N rock that you carry horizontally across a 8-m room?
 a. 80 J b. 8 J c. 0 J d. 10 J e. 1 J

30

Kinetic energy of an object is equal to
 a. its mass multiplied by its speed. b. one half the product of its mass times its speed squared. c. one half the product of its mass times its speed. d. its mass multiplied by its acceleration. e. its mass multiplied by its acceleration squared.