# Topic 2 - Motion and Forces COMPLETE PK Flashcards

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1
Q

1 Runner A finishes a race in less time than runner B. Who is faster?

A

runner A

2
Q

2 What two measurements are needed to calculate a speed?

A

distance and time

3
Q

3 What is the SI unit for speed?

A

m/s

4
Q

4 What does acceleration mean?

A

speeding up or slowing down

5
Q

5 What is a force?

A

push or pull

6
Q

6 How do we represent forces on diagrams?

A

arrows, with length depending on size of force

7
Q

7 What does mass mean?

A

amount of substance

8
Q

8 What is the unit for mass?

A

kilogram

9
Q

9 What does a vector have that a scalar does not?

A

direction

10
Q

10 Name a scalar and a vector measured in metres.

A

distance, displacement

11
Q

11 Name a scalar and a vector measured in metres/second.

A

speed, velocity

12
Q

12 Name a vector with units of newtons.

A

force or weight

13
Q

13 Is mass a vector or scalar?

A

scalar

14
Q

14 Is energy a vector or scalar?

A

scalar

15
Q

15 What is acceleration?

A

a change in velocity

16
Q

16 Why is acceleration a vector?

A

it is measuring a change in another vector

17
Q

17 What is the difference between speed and velocity?

A

velocity has a direction/is a vector

18
Q

18 What is the equation for calculating speed?

A

speed = distance / time

19
Q

19 What is the SI unit for speed?

A

metres per second

20
Q

20 What is average speed?

A

total distance / time for whole journey

21
Q

21 What is the equation for calculating distance?

A

distance = speed x time

22
Q

22 How is a constant speed shown on a distance/time graph?

A

straight, sloping line

23
Q

23 What does a horizontal line on a distance/time graph show?

A

stationary object

24
Q

24 What is the speed of sound in air?

A

approximately 330m/s

25
Q

25 How is a stationary object shown on a distance/time graph?

A

horizontal line

26
Q

26 How can you tell which part of a journey shown on a distance/time graph has the highest speed?

A

steepest line

27
Q

27 How can you calculate velocity from a distance/time graph?

A

28
Q

28 What does acceleration mean?

A

change in velocity in time

29
Q

29 What are the units for acceleration?

A

metres per second squared

30
Q

30 In the acceleration equation, what does u stand for?

A

initial velocity

31
Q

31 In the acceleration equation, what does v stand for?

A

final velocity

32
Q

32 What is the equation for calculating acceleration?

A

change in velocity/time, or

33
Q

33 What is the acceleration due to gravity?

A

10m/s2 to 1 sig. fig or 9.8m/s2 to 2 sig. fig.

34
Q

34 What is the force that pulls us towards the Earth?

A

gravity

35
Q

35 What is ‘drag’ another name for?

A

air resistance or water resistance

36
Q

36 What are balanced forces?

A

forces of the same size in opposite directions

37
Q

37 What do we call the forwards force produced by an aeroplane’s engine or propeller?

A

thrust

38
Q

38 What word describes both the speed and direction of movement of an object?

A

velocity

39
Q

39 What is the name for a single force on an object with the same effect as all the forces combined?

A

resultant

40
Q

40 How do we describe the forces on an object when the force in one direction is bigger than the force in the other?

A

unbalanced

41
Q

41 Two forces on an object are in the same direction. How do we calculate the resultant force?

A

42
Q

42 Two forces on an object are in opposite directions. How do we calculate the resultant force?

A

find the difference between them

43
Q

43 What does the length of a force arrow on a diagram represent?

A

size of force

44
Q

44 An aeroplane has thrust of 2000N and drag of 1800N. What is the resultant?

A

200N forwards

45
Q

45 Air resistance on a cyclist is 20N and friction is 5N. What is the total force trying to slow the cyclist down?

A

25N backwards

46
Q

46 Name a vector quantity that changes as a car drives at constant speed around a roundabout.

A

velocity

47
Q

47 What are unbalanced forces?

A

forces of different sizes in opposite directions

48
Q

48 What is the direction of the resultant force on a car that is speeding up?

A

forwards

49
Q

49 What is the direction of the resultant force on a bicycle that is slowing down?

A

backwards

50
Q

50 How does a sideways resultant force affect the velocity of a moving object?

A

changes its direction

51
Q

51 How can the pilot of an aeroplane make the plane gain speed upwards?

A

increase the lift/upwards force

52
Q

52 How do balanced forces affect the velocity of a moving car?

A

The car continues with the same velocity.

53
Q

53 You pedal harder on a bicycle. What happens?

A

you accelerate/get faster

54
Q

54 H What is the name of the force that makes objects move in a circular path?

A

centripetal

55
Q

55 H What provides the centripetal force for a car going around a roundabout?

A

friction

56
Q

56 H What are the forces on a moon orbiting around a planet?

A

gravity acting towards the planet

57
Q

57 H In which direction does centripetal force act?

A

towards the centre of the circle .

58
Q

58 Why is the force of gravity greater on a lorry than on a car?

A

larger mass

59
Q

59 Why is the resultant force accelerating a car usually less than the force provided by its engine?

A

air resistance and/or friction

60
Q

60 Name one force that usually has to be taken into account when working out the resultant force on a moving object

A

drag or friction

61
Q

61 When will a resultant force act to slow a car down?

A

when backwards forces are greater than forwards ones

62
Q

62 How can friction act to make a car speed up?

A

63
Q

63 How can friction act to make a car slow down?

A

in brakes

64
Q

64 What is the formula linking force, mass and acceleration?

A

F = m x a

65
Q

65 An object is moving at a constant velocity. What can you say about the forces on it?

A

balanced

66
Q

66 What is the equation relating these factors?

A

speed = distance / time

67
Q

67 What type of force is used to slow down a moving vehicle?

A

friction

68
Q

68 Where is this force applied?

A

brakes, tyres

69
Q

69 Why is a wet road more slippery than a dry one?

A

water acts as lubricant

70
Q

70 An object has a negative acceleration. What does this mean?

A

it is slowing down

71
Q

71 What effect does drinking alcohol have on human reaction times?

A

slows them down/makes them longer

72
Q

72 How will being tired affect reaction time?

A

make it longer

73
Q

73 What does ?braking distance? mean?

A

the distance a car travels while slowing down

74
Q

74 What does ?thinking distance? mean?

A

the distance a car travels while the driver is reacting to a danger and deciding to apply the brakes

75
Q

75 How does speed affect the thinking distance?

A

higher speed, longer thinking distance/thinking distance directly proportional to speed

76
Q

76 How does speed affect the braking distance?

A

higher speed, longer braking distance/braking distance proportional to speed squared

77
Q

77 How does the force needed for an acceleration depend on the size of the acceleration?

A

larger acceleration, larger force needed

78
Q

78 What does deceleration mean?

A

slowing down/a negative acceleration

79
Q

79 H What factors affect the momentum of a moving object?

A

mass, velocity

80
Q

80 H How does the mass affect momentum?

A

higher mass, higher momentum

81
Q

81 H How does the velocity affect momentum?

A

higher velocity, higher momentum

82
Q

82 H What does momentum is conserved mean?

A

total momentum is the same before and after a collision

83
Q

What is a scalar quantity?

A

A force with just magnitude

84
Q

What is a vector quantity?

A

A force with both direction and magnitude

85
Q

Is distance vector or scalar?

A

Scalar

86
Q

Is mass vector or scalar?

A

Scalar

87
Q

Is speed vector or scalar?

A

Scalar

88
Q

Is displacement vector or scalar?

A

Vector

89
Q

Is weight vector or scalar?

A

Vector

90
Q

Is velocity vector or scalar?

A

Vector

91
Q

Is acceleration vector or scalar?

A

Vector

92
Q

Is force vector or scalar?

A

Vector

93
Q

Is momentum vector or scalar?

A

Vector

94
Q

How do you find the gradient of a line on a graph?

A

Change in y / change in x

95
Q

What does a horizontal line in a velocity/time graph mean?

A

96
Q

What does a / line in a velocity/time graph mean?

A

Acceleration

97
Q

In a velocity/time graph, what is acceleration equal to?

A

98
Q

How do you calculate the gradient in a velocity/time graph?

A

Change in y / change in x (velocity / time)

99
Q

How do you find distance travelled in a velocity/time graph?

A

Calculate the area under the graph

100
Q

How do you calculate acceleration from velocities?

A

Acceleration = (final velocity - initial velocity)

time taken

101
Q

final velocity2 - initial velocity2 =

A

2 x acceleration x distance

102
Q

What is the value of gravity on earth?

A

10 N/kg

103
Q

Is the value of gravity on earth more or less than the value of gravity on the moon?

A

Less

104
Q

If you are falling on earth, what is your acceleration due to gravity?

A

10m/s squared

105
Q

What is the resultant force?

A

Difference between two forces in different directions - equal to the sum to all forces applied on an object

106
Q

Force =

A

mass x acceleration

107
Q

Weight =

A

mass x gravity

108
Q

A

will change depending on gravity - ie if you are on a different planet

109
Q

What is centripetal force?

A

The resultant force when things are moving in a circle

110
Q

Things moving in a circle due to centripetal force have a constant/changing speed and a constant/changing velocity

A

constant speed, changing velocity

111
Q

When things move in a circle, why does the velocity change?

A

Velocity is speed in a certain direction

112
Q

Momentum =

A

mass x velocity

113
Q

What is the law of conservation of momentum?

A

Momentum is always conserved

114
Q

F = mv - mu

?

A

t

115
Q

Momentum before =

A

momentum afterwards

116
Q

Stopping distance =

A

thinking distance + breaking distance

117
Q

The faster you are going, the more the thinking distance and breaking distance increases/decreases

A

Increases

118
Q

Why does thinking distance increase the faster you are going?

A

Your brain needs to firstly see the image, the signal needs to be sent to your brain, processed and then sent to your foot. The faster you are going the more distance you will travel in the time that takes

119
Q

Name 2 things that have an effect on thinking distance

A

Any 2 from alcohol, drugs, tiredness and caffeine

120
Q

Does taking illegal drugs have a positive or negative impact on thinking distance?

A

Negative

121
Q

Does tiredness have a positive or negative impact on thinking distance?

A

Negative

122
Q

Does drinking alcohol have a positive or negative impact on thinking distance?

A

Negative

123
Q

Does caffeine have a positive or negative impact on thinking distance?

A

Positive

124
Q

Name 2 things that have an effect on breaking distance

A

Any 2 from the condition of the tyres, the condition of the road and the weight of the car

125
Q

What impact does the condition of tyres have on breaking distance?

A

New tyres will stop much quicker than old tyres which don’t have much grip on the road

126
Q

What impact does the condition of the road have on breaking distance?

A

A snowy/icy road or a road that has a lot of grit on it is going to have a much longer breaking distance than a new road

127
Q

What impact does the weight of the car have on breaking distance?

A

A heavier car is gong to take much longer to stop

128
Q

What impact does the weight of the car have on breaking distance?

A

A heavier car is gong to take much longer to stop

129
Q

What is kinetic energy measured in?

A

Joules (J)

130
Q

distance =

A

speed x time

131
Q

kinetic energy =

A

1/2 x mass x velocity2

132
Q

work done =

A

force x distance

133
Q
A