Deck 4: Work and Energy

Question 1

A 4-kg object falls vertically a distance of 5 m.Its potential energy has changed by approximately how much?

A) It has increased by 20 J.
B) It has decreased by 200 J.
C) It has decreased by 20 J.
D) It has increased by 200 J.

Answer 1

B

Question 2

The quantity $\frac { 1 } { 2 } m v ^ { 2 }$ is known as

A) kinetic energy.
B) potential energy.
C) work.
D) energy.
E) power.

Answer 2

kinetic energy.

Question 3

Which of the following is a vector quantity?

A) Force
B) Power
C) Work
D) Time
E) None of these

Answer 3

A

Question 4

A student weighing 300 N climbed a flight of stairs 5.0 m high in 6 s.How much work was done by the student?

A) 1500 J
B) 1800 J
C) 1500 W
D) 1800 W
E) 50 W

Question 5

The kinetic energy of a pendulum is greatest

A) when its potential energy is greatest.
B) at the top of its swing.
C) at the bottom of its swing.
D) when its total energy is greatest.

Question 6

An object of mass 2 kg has a speed of 8 m/s and moves a distance of 6 m.What is its kinetic energy in joules?

A) 64
B) 48
C) 289
D) 16

Question 7

A joule per second (J/s)is a

A) Watt.
B) Newton.
C) Kilogram.
D) Second.

Question 8

The energy of motion is called

A) inertia.
B) power.
C) kinetic energy.
D) potential energy.

Question 9

An object has kinetic energy of 324 J.If its speed is 9 m/s,what is its mass?

A) 8
B) 36
C) 1620
D) 324

Question 10

Work is defined as force times

A) distance.
B) time.
C) parallel distance.
D) perpendicular distance.

Question 11

The potential energy of a pendulum is least

A) when its potential energy is greatest.
B) at the top of its swing.
C) at the bottom of its swing.
D) when its total energy is greatest.

Question 12

When a 6-kg object increases its potential energy by 180 J,approximately how has its position changed?

A) It has risen vertically 3 m.
B) It has fallen vertically 3 m.
C) It has risen vertically 30 m.
D) It has moved horizontally 30 m.

Question 13

Which of the following is not a unit of work?

A) ft · lb
B) N · m
C) joule
D) watt

Question 14

A joule/meter (J/m)is a unit of

A) force.
B) work.
C) energy.
D) power.

Question 15

A 1000-kg car traveling at 70 m/s takes 3 m to stop under full braking.The same car under similar road conditions,traveling at 140 m/s,takes ______________ m to stop under full braking.

A) 6
B) 1
C) 3
D) 12
E) 11

Question 16

The ______________ distance is used in calculating work.

A) normal
B) square of
C) perpendicular
D) parallel

Question 17

The kinetic energy of a pendulum is least

A) when its potential energy is least.
B) at the top of its swing.
C) at the bottom of its swing.
D) when its total energy is greatest.

Question 18

Which of the following is a vector quantity?

A) Energy
B) Power
C) Work
D) None of these

Question 19

Work requires

A) motion.
B) zero net force.
C) zero momentum.
D) a force perpendicular to the direction of motion.

Question 20

A student weighing 200 N climbs a flight of stairs 9.0 m high in 4 s.What power is required to perform this task?

A) 1800 J
B) 800 J
C) 1800 W
D) 800 W
E) 450 W

Question 21

If you lift a 15-N weight vertically 30 m above the ground,you are

A) doing work against gravity.
B) doing work against friction.
C) doing work against inertia.
D) doing none of these.

Question 22

Which of the following four objects has different kinetic energy?

A) An object of mass m moving with speed 4v
B) An object of mass 4m moving with speed 2v
C) An object of mass 16m moving with speed v
D) An object of mass 2m moving with speed 3v
E) None of these; all four objects have the same kinetic energy.

Question 23

The energy of a system

A) always increases.
B) always remains constant.
C) increases when work is done by the system.
D) increases when work is done on the system.

Question 24

Mechanical energy

A) is always the total energy of a system.
B) is the sum of the energies of motion and position.
C) is always conserved.
D) necessarily involves gravitational potential energy.

Question 25

Power is

A) the time rate of doing work.
B) the time rate of doing velocity.
C) the time rate of doing momentum.
D) the time rate of doing force.

Question 26

One watt is equal to one joule per ______________.

A) second
B) newton
C) hour
D) kilogram

Question 27

The energy of position is called

A) potential energy.
B) power.
C) kinetic energy.
D) heat.

Question 28

Potential-energy values may be

A) positive only.
B) negative only.
C) zero only.
D) all of these.

Question 29

A system may

A) be isolated.
B) have real boundaries.
C) have imaginary boundaries.
D) all of these

Question 30

Which of the following is not a unit of power?

A) ft · lb/s
B) kW · h
C) J/s
D) watt

Question 31

Which of the following is not a unit of power?

A) ft · lb/s
B) N · m
C) J/s
D) watt

Question 32

We define the total mechanical energy of an object as

A) potential energy plus kinetic energy.
B) inertial energy plus kinetic energy.
C) gravitational energy plus potential energy.
D) mental energy plus physical energy.

Question 33

The potential energy of a pendulum is greatest

A) when its potential energy is least.
B) at the top of its swing.
C) at the bottom of its swing.
D) when its total energy is greatest.

Question 34

Mechanical energy

A) is the automobile energy.
B) is the sum of kinetic and potential energies.
C) is the kinetic energy.
D) is the potential energy.

Question 35

Power is

A) work divided by time.
B) velocity multiplied by time.
C) momentum divided by time.
D) energy multiplied by time.

Question 36

Which of the following four objects has the least kinetic energy?

A) An object of mass m moving with speed 4v
B) An object of mass 3m moving with speed 2v
C) An object of mass 4m moving with speed v
D) An object of mass 2m moving with speed 3v
E) None of these; all four objects have the same kinetic energy.

Question 37

Which of the following four objects has the greatest kinetic energy?

A) An object of mass m moving with speed 4v
B) An object of mass 3m moving with speed 2v
C) An object of mass 4m moving with speed v
D) An object of mass 2m moving with speed 3v
E) None of these; all four objects have the same kinetic energy.

Question 38

One watt is equal to ______________ per second.

A) one kilogram
B) one newton
C) one joule
D) one meter

Question 39

The energy of a system

A) always increases.
B) always remains constant.
C) decreases when work is done by the system.
D) decreases when work is done on the system.

Question 40

One ______________ is equal to one joule per second.

A) kilogram
B) newton
C) pound
D) watt

Question 41

Energy provided directly from Earth's interior is called

A) groundwater energy.
B) geothermal energy.
C) artesian energy.
D) thermionic energy.

Question 42

Currently,in the United States,which fuel has the largest consumption?

A) Oil
B) Natural gas
C) Coal
D) Nuclear

Question 43

The largest reserve of energy in the United States is in what form?

A) Oil
B) Natural gas
C) Coal
D) Nuclear

Question 44

One positive aspect of the potential use of methane hydrate as a fuel is that

A) there is more of it than there is of coal, oil, and natural gas.
B) it is easy to mine.
C) its use will never contribute to global warming.
D) it exists in a pure form ready for use.

Question 45

Which of the following is not a scalar quantity?

A) Kinetic energy
B) Potential energy
C) Power
D) Work
E) None of these; that is, they are all scalar quantities.

Question 46

The average adult radiates heat energy at the same rate as

A) a 10-W light bulb.
B) a 100-kW light bulb.
C) a 100-W light bulb.
D) none of these.

Question 47

For which of the following reasons is production of ethanol unwise?

A) Pollutants aren't significantly reduced.
B) It takes twice as much fossil-fuel energy to produce ethanol than the ethanol that is produced supplies.
C) It can drive costs of corn higher.
D) All of the above.

Question 48

Currently,in the United States,which fuel is utilized to produce the majority of electrical power?

A) Oil
B) Natural gas
C) Coal
D) Nuclear

Question 49

"Ice that burns" is better known as

A) propane.
B) frozen oil.
C) coal.
D) methane hydrate.

Question 50

Although the United States has less than 5% of the world's population,it accounts for approximately ______________ of the world's annual consumption of fossil fuels.

A) 15%
B) 25%
C) 35%
D) 45%

Question 51

Currently,in the United States,which sector of the economy uses the most energy?

A) Industry
B) Transportation
C) Commercial
D) Residential

Question 52

Which of the following is(are)drawbacks to the use of methane hydrate as a fuel?

A) When melted, it produces methane, a greenhouse gas.
B) It is difficult to mine as a solid located at the bottom of the oceans.
C) It is mixed with water.
D) All of these are drawbacks associated with methane hydrate.

Question 53

It is estimated that the global reserve of methane hydrate is ______________ the global reserves of coal,oil,and natural gas.

A) equal to
B) less than
C) twice
D) ten times

Question 54

Which of the following is a unit of power?

A) kilowatt-hour
B) newton
C) joules per second
D) foot-pound
E) none of these

Question 55

Some food costs may rise in the future as a consequence of the increased use of which food-based fuel?

A) Ethanol
B) Gasoline
C) Oil
D) Coal

Question 56

Which of the following sources of energy presents the fewest pollution problems under normal operating conditions?

A) Coal
B) Natural gas
C) Nuclear fission
D) Hydroelectric power

Question 57

A kilowatt-hour is a unit that measures

A) work per unit of time.
B) energy.
C) power.
D) work × time.

Question 58

A mixture of ethanol and gasoline is called

A) ethaline.
B) gasanine.
C) gasohol.
D) gethanine.

Question 59

What is bought from an electric company?

A) Electrical energy
B) Electric charge
C) Electrical power
D) None of these

Question 60

Which of the following is a unit of energy?

A) kilowatt-hour
B) newton
C) joules per second
D) newton-second
E) none of these

Question 61

The kilowatt-hour is a unit of ______________.

Question 62

Energy resulting from motion is called ______________.

Question 63

When the kinetic energy of a simple pendulum decreases,the ______________ of the pendulum increases.

Question 64

A system for which there are no outside effects is said to be ______________.

Question 65

Work is the process by which energy is ______________.

Question 66

In pushing an object on a level surface,work is done against ______________.

Question 67

Kinetic and potential energies are forms of ______________ energy.

Question 68

The sum of the kinetic energy and potential energy is called ______________ energy.

Question 69

In changing from one form to another,energy is always ______________.

Question 70

The units of work are the same as those of ______________.

Question 71

According to the law of conservation of energy,energy cannot be ______________ or ______________.

Question 72

When the height of an object is doubled,its gravitational potential energy is increased by a factor of ______________.

Question 73

When a moving object's velocity doubles,its kinetic energy increases by a factor of ______________.

Question 74

The product of one ______________ and one meter is one joule.

Question 75

The kinetic energy of a pendulum is ______________ at the bottom of its swing.

Question 76

The process by which electricity can be generated by using running or falling water is known as

A) groundwater generation.
B) hydroelectric generation.
C) geothermal generation.
D) steam generation.

Question 77

In lifting an object,work is done against ______________.

Question 78

The two types of mechanical energy are ______________ and ______________.

Question 79

The value of an object's gravitational potential energy depends on the ______________.

Question 80

The product of force times parallel distance is called ______________.