Work And Power Flashcards

1
Q

What is the equation for work done?

A

Work done = force x distance moved in direction of force

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2
Q

What are units for work done?

A

Joules, J

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3
Q

What are the units for force?

A

Newtons, N

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4
Q

What are the units used for distance moved in direction of force?

A

Meters, m

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5
Q

What is power?

A

Power is the rare of energy transferred

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6
Q

What is the equation for speed?

A

Speed = distance/ time

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7
Q

What is the equation for power?

A

Power = work done/time taken

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8
Q

What is power measured in?

A

Watts, w

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9
Q

What is time taken measured in?

A

Seconds, s

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10
Q

1 watt = ? j/s

A

1 watt = 1 J/s

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11
Q

What could work done also be seen as?

A

Energy

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12
Q

What is equilibrium?

A

Where the forces on opposite sides are balanced and the objects are either balanced or moving at a constant speed

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13
Q

What are contact forces?

A

Objects affecting each other by touching

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14
Q

What are the three contact forces?

A

Push, pull, friction

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15
Q

What are non contact forces?

A

Forces affecting each other without touching

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16
Q

What are the three non contact forces?

A

Gravity, magnetic fields, electrostatic forces

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17
Q

Where do gravitational fields effect?

A

Around anything with mass

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18
Q

Where do electrostatic fields effect?

A

Around any charged object

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19
Q

Where do magnetic fields effect?

A

Around any magnet

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20
Q

What are the four rules of force pairs?

A

They do not cancel each other out
They act in different objects
They are the same size
They act in opposite directions

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21
Q

What is Newton’s third law?

A

For every force there’s an equal opposite reaction force

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22
Q

What are force pairs an example of?

A

Newton’s third law pairs

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23
Q

What type of force would a chair pushing up on you be?

A

Normal contact force

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24
Q

What are the three rules for forces on a single object?

A

May be the same type or different types
May cancel each other out (balanced
May not cancel each other out (unbalanced

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25
Q

What is weight?

A

The earth pulling (object) down. Caused by gravity

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26
Q

How can we draw a diagram to show vector forces?

A

Using arrows pointing in the correct direction in a scale diagram

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27
Q

What is a scalar quantity?

A

A scalar quantity has only a size (magnitude) and doesn’t have a direction

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28
Q

What’s an example of a scalar quantity?

A

Distance

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29
Q

What is a vector quantity?

A

A vector quantity has a size (magnitude) and a direction

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30
Q

What is an example of a vector quantity?

A

Displacement

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31
Q

Is charge a vector or scalar quantity?

A

Scalar

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32
Q

Is distance a vector or scalar quantity?

A

Scalar

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33
Q

Is energy a vector or scalar quantity?

A

Scalar

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34
Q

Is frequency a vector or scalar quantity?

A

Scalar

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35
Q

Is mass a vector or scalar quantity?

A

Scalar

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36
Q

Is pressure a vector or scalar quantity?

A

Scalar

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37
Q

Is speed a vector or scalar quantity?

A

Scalar

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38
Q

Is temperature a vector or scalar quantity?

A

Scalar

39
Q

Is time a vector or scalar quantity?

A

Scalar

40
Q

Is volume a vector or scalar quantity?

A

Scalar

41
Q

Is acceleration a vector or scalar quantity?

A

Vector

42
Q

Is displacement a vector or scalar quantity?

A

Vector

43
Q

Is electric current a vector or scalar quantity?

A

Vector

44
Q

Is field strength a vector or scalar quantity?

A

Vector

45
Q

Is force a vector or scalar quantity?

A

Vector

46
Q

Is moment a vector or scalar quantity?

A

Vector

47
Q

Is momentum a vector or scalar quantity?

A

Vector

48
Q

Is velocity a vector or scalar quantity?

A

Vector

49
Q

Is weight a vector or scalar quantity?

A

Vector

50
Q

What are the two average speeds of motorway speed limits?

A

31m/s and 70mph

51
Q

What are the two average speeds of walking?

A

1.4m/s and 3.1mph

52
Q

What are the two average speeds of cycling?

A

6m/s and 13mph

53
Q

What are the two average speeds of airplane?

A

230m/s and 340mph

54
Q

What are the two average speeds of speed limit in town?

A

13m/s and 30mph

55
Q

What are the two average speeds of commuter train?

A

55m/s and 123mph

56
Q

What are the two average speeds of sound?

A

342m/s and 515mph

57
Q

What does speed tell you about an object

A

How quickly it travels a certain distance

58
Q

What are the three units of speed?

A

Km/h, m/s, mph

59
Q

What are the two scientific meanings of ‘fast?

A

Travel further in the same time or travel the same distance in less time

60
Q

Speed equation

A

Speed = distance / time

61
Q

Units for speed

A

m/s

62
Q

Units for distance

A

m

63
Q

Units for time

A

s

64
Q

In the triangle, what is distance represented by?

A

The letter x

65
Q

What do we use distance time graphs for?

A

To represent a journey in an easy way

66
Q

What is velocity equation?

A

Velocity = displacement / time

67
Q

What is acceleration equation?

A

Change in velocity / time

68
Q

When does velocity changes?

A

When direction changes

69
Q

What types of velocity can you have?

A

Positive and negative

70
Q

Average speed equation

A

Total distance / time for whole journey

71
Q

What are two base rules of acceleration ?

A

Always has a direction, can be positive or negative

72
Q

What is units for acceleration?

A

m/s^2

73
Q

What is change in velocity units?

A

m/s

74
Q

What is time units?

A

s

75
Q

What are the letter/triangle equation for acceleration?

A

a= v-u/t

76
Q

What does the letter v represent?

A

Final velocity

77
Q

What does the letter u represent?

A

Staring velocity

78
Q

How do you work out change in velocity?

A

Final velocity - starting velocity

79
Q

What happens to the acceleration of an object when the velocity changes?

A

It accelerates

80
Q

An airliners velocity changes from 0m/s to 60m/s in 20 seconds. What is it’s acceleration?

A

a=v-u/t = 60-0/20 =3m/s^2

81
Q

If an object is slowing down, what happens to its acceleration?

A

It’s decelerating, will have a negative acceleration

82
Q

What is acceleration due to gravity?

A

10

83
Q

What is the acceleration equation?

A

(Final velocity)^2 - (initial velocity)^2 = 2x acceleration x distance

V^2-u^2=2xax x

84
Q

A car travelling at 15 m/s accelerates at 1.5m/s^2 over a distance of 50m. Calculate it’s final velocity.

A
V^2=(2xax x) + u^2
=(2x1.5x50)+(15x15)
V^2= 375(m/s)^2
V = (square root of 375) m/s^2
=19.4 m/s
85
Q

What are SI units for velocity?

A

M/s

86
Q

What are SI units for acceleration?

A

M/s^2

87
Q

A cyclist accelerates from 2m/s to 8m/s with an acceleration of 1.5m/s^2. How far did she travel while she was accelerating? Use the formula: x=(v^2-u^2)/2xa

A

X=(8^2-2^2)/2x1.5

X=64-4/3
X=20m

88
Q

On a velocity time graph, how do you work out the distance travel?

A

Area of the graph (under the line)

89
Q

How is acceleration represented in a velocity time graph?

A

The gradient of the line

90
Q

If the line is going downwards on a velocity time graph, what does it mean?

A

Negative velocity

91
Q

If the angle on the road is changing while a car is driving , what does this mean for direction mad velocity?

A

They’re both changing

92
Q

A car drives around a roundabout at 30km/h. How is speed effected? How is velocity effected? How is acceleration effected?

A

Speed stays the same
Velocity is changing because care is moving in a different direction
It is accelerating because velocity is changing

93
Q

How do you work out resultant force?

A

Subtract all relevant forces from each other

94
Q

An object has a resultant force of 0N. What does this mean?

A

It’s stationary or moving at constant speed