Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Preparation for Physics Final > Chapter 9 > Flashcards

Chapter 9 Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

What is work?

A

The product of the net force on an object
and the distance through which the object is moved.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Do we do work when we lift a load against Earth’s gravity?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The _______the load or the ________we lift it, the more _______we do.

A

heavier; higher; work

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

______ is done when a ______ acts on an _______ and the object moves in the _______ of the force.

A

Work; force; object; direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the equation of Work?

A

W=Fd

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

If we lift two loads up one story, we do _____ as much _____as we would in lifting one load the same distance

A

twice; work

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

If we lift one load two stories instead of one story, we do _____ as much work because the ______ is twice as great

A

twice; distance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Is work done if the object is not moved by the exerted force and in the direction of the force?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

If a weighlifter is holding the barbell in the air, there is not work on the barbell. Where is work done?

A

On the muscles by stretching and squeezing them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How many categories does work fall into to?

A

two

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

11). What is one of the categories work falls into?

A

Work done against another force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Example of #11

A

When an archer stretches her bowstring, she is doing work against the elastic forces of the bow. Push-ups (against the force of your own weight)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

You do _____ on something when you force it to move _______ the influence of an _______ force—often friction.

A

work; against; opposing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

14). The other category of work is work done to…

A

change the speed of an object

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Example of #14

A

bringing an automobile up to speed or in slowing it down.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

In both categories, work involves __________between something and its surroundings.

A

a transfer of energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the unit of work?

A

Joule (J)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Does the definition of work say something about how long it takes to do the work?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

When carrying a load up some stairs, do you do the same amount of work whether you walk or run up the stairs?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does power equal?

A

Power equals the amount of work done divided by the time interval during which the work is done.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Does a high powered engine do work rapidly?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Does an automobile engine that delievers twice the power of another automobile produce twice as much work or go twice as fast as the less powerful engine?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Twice the power means…

A

It can do twice as much work in the same amount of time or the same amount of work in half the time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the unit of power

A

J/s or watts (W)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Why was Watt named Watt?

A

In honor of James Watt, the 18th century developer of the steam engine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

One kilowatt equals…

A

1000W

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

In the U.S., we rate engines in units of..

A

Horsepower and electricity kilowatts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

One horsepower(hp) is the same as…

A

0.75kW

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

When work is done by an archer in drawing back a bowstring, the bent bow acquires…

A

the ability to do work on the arrow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

In what situations may an object acquire the ability to do work?

A

ompression of atoms in the material of an object; a physical separation of attracting bodies; or a rearrangement of electric charges in the molecules of a substance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Energy

A

The property of an object or system that enables it to do work

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is energy measured in?

A

Joules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Mechanical energy

A

the energy due to the position of something or the movement of something

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are two forms of mechanical energy

A

Kinetic and Potential Energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Potential Energy

A

Energy that is stored and held in readiness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What are three examples of potential energy?

A

elastic potential energy, chemical energy, and gravitational potential energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What type of energy does a stretched or compressed spring have?

A

Elastic Potential Energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is elastic potential energy?

A

When an object has the ability to do work bc of its position.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Are the chemical energy in fuels also potential energy?

A

Yes

40
Q

What is chemical energy?

A

energy of position at the submicroscopic level

41
Q

When is chemical energy available?

A

when the positions of electric charges within and between molecules are altered, that is, when a chemical change takes place.

42
Q

Gravitational Potential energy

A

The potential energy due to elevated positions

43
Q

What is the amount of gravitational potential energy possessed by an elevated object is equal to…

A

the work done against gravity in lifting it

44
Q

Gravitational potential energy’s formula is…

A

mgh

45
Q

The gravitational potential energy is relative to that ________and depends only on mg and h

A

level

46
Q

If you’re in a third-story classroom and a ball rests on the floor, you can say the ball is at height ___. Lift it and it has ________ PE relative to the floor. Toss it out
the window and it has __________ PE relative to the floor

A

0; positive; negative

47
Q

How do hydroelectric power stations make use of gravitational potential energy?

A

Water from an upper reservoir flows through a long tunnel to an electric generator.

48
Q

Gravitational potential energy of water is converted into…

A

electrical energy

49
Q

If an object is moving, is it capable of doing work?

A

Yes

50
Q

What is kinetic energy

A

Energy of motion

51
Q

The ____________ of a moving object is ______ to the work required to bring it to its speed from rest, or the work the object can do while being brought to rest

A

Kinetic Energy; equal

52
Q

If the speed is squared (doibled) the kinetic energy is…

A

quadrupled and takes 4x as much work to stop

53
Q

What does the work energy theorem state?

A

whenever work is done, energy changes

54
Q

Work =…

A

change in kinetic energy

55
Q

What does the work-energy theorem emphasizes?

A

the role of change

56
Q

If there is no change in a object’s KE, the no ______was done on it.

A

net work

57
Q

The net force minus the frictional force times the distance equals…

A

KE

58
Q

Is the force of friction an independent variable?

A

Yes

59
Q

How does kinetic energy appear?

A

heat, sound, light, and electricity

60
Q

What does the law if conservation of energy state?

A

Energy cannot be created or destroyed. It can be transformed from one form into another, but the total amount of energy never changes.

61
Q

Energy may change form, but…

A

the total energy score stays the same

62
Q

Each atom that makes up matter is a…

A

concentrated bundle of energy

63
Q

Enormous compression due to gravity in the deep hot interior of the sun causes hydrogen nuclei to…

A

fuse and become helium nuclei

64
Q

What dies thermonuclear fusion due?

A

It releases radiant energy

65
Q

Machine

A

A device used to multiply forces or simply to change the direction of forces.

66
Q

A machine ________ energy from one place to another or _________ it from one form to another

A

transfers; transforms

67
Q

Lever

A

a simple machine made of a bar that turns about a fixed point

68
Q

The work input of a lever equals the….

A

work out (if the friction is small enough to neglect)

69
Q

The fd(in) of the lever equals the…

A

fd(out)

70
Q

What is the fulcrum?

A

The pivot point

71
Q

The ratio of output force to input force is called the…

A

mechanical advantage

72
Q

Type 1 lever

A
  • fulcrum is betwen force and loas
  • seesaw
  • push down on onw end and lift load at other
  • increase force at expense of distance
  • directions of input and output are opposite
73
Q

Type 2 lever

A
  • load is between fulcrum and input force
  • to lift load, you lift end of lever
  • force on load is increased at expense of distance
  • forces have same direction
74
Q

Type 3 lever

A
  • fulcrum is at one end and load is at other
  • input force is applied between them
  • bicep muscles to arms
  • increases distance at expense of force
  • biceps move short distance, arms move longer distance
  • input and output forces are no the same side of the fulcrum, i.e. have same direction
75
Q

pulley

A

a kind of lever that can be used to change the direction of a force

76
Q

Can a pulley or system of pulleys multiply the force?

A

Yes

77
Q

The mechanical advantage for simple pulley is the same as the number of __________________________________.

A

strands of rope that actually support the load

78
Q

Can a machine be 100% efficient?

A

No

79
Q

In any machine, some energy is _________into ________ or _________kinetic energy, which makes the machine warmer.

A

transformed; atomic; molecular

80
Q

The efficiency of a machine is…

A

the ratio of useful energy output to total energy input, or the percentage of the work input that is converted to work output

81
Q

Is an inclined plane a machine?

A

Yes

82
Q

What can efficiency also be expressed as?

A

actual mechanical advantage/ theoretical mechanical advantage

83
Q

Will efficiency always be a fraction less than 1?

A

Yes

84
Q

An automobile is a machine that transforms _______________stored in fuel into _________________.

A

chemical energy; mechanical energy

85
Q

Burning is a chemical reaction in which ______________________.

A

atoms combine with oxygen, and energy is released

86
Q

Is transforming 100% of thermal energy into mechanical energy possible?

A

No

87
Q

Does friction add more to the energy loss?

A

Yes

88
Q

Is every living cell in every organism a machine?

A

Yes

89
Q

Is there more energy stored in the molecules oin food than there is in the reaction products after the food is metabolized?

A

Yes

90
Q

What is the source of practically all our energy on Earth?

A

The sun, nuclear, and geothermal energy

91
Q

How is sunlight directly transformed into electricity?

A

Photovoltaic cells

92
Q

Is hydrogen the least polluting of all fuels?

A

Yes

93
Q

Does it take energy to make hydrogen? If so, why?

A

Yes, bc it is extracted from water and carbon compounds

94
Q

Where is the most concentrated form of usable energy stored in?

A

Uranium and plutonium, which are nuclear fuel

95
Q

What is geothermal energy a byproduct of?

A

Radioactivity in Earth’s interior

96
Q

Where is geothermal energy held?

A

In underground reservoirs of hot water

Preparation for Physics Final (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions