Topic 2 - Motion and Forces COMPLETE PK Flashcards
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
25 How is a stationary object shown on a distance/time graph?
horizontal line
26
26 How can you tell which part of a journey shown on a distance/time graph has the highest speed?
steepest line
27
27 How can you calculate velocity from a distance/time graph?
gradient of line
28
28 What does acceleration mean?
change in velocity in time
29
29 What are the units for acceleration?
metres per second squared
30
30 In the acceleration equation, what does u stand for?
initial velocity
31
31 In the acceleration equation, what does v stand for?
final velocity
32
32 What is the equation for calculating acceleration?
change in velocity/time, or
33
33 What is the acceleration due to gravity?
10m/s2 to 1 sig. fig or 9.8m/s2 to 2 sig. fig.
34
34 What is the force that pulls us towards the Earth?
gravity
35
35 What is 'drag' another name for?
air resistance or water resistance
36
36 What are balanced forces?
forces of the same size in opposite directions
37
37 What do we call the forwards force produced by an aeroplane's engine or propeller?
thrust
38
38 What word describes both the speed and direction of movement of an object?
velocity
39
39 What is the name for a single force on an object with the same effect as all the forces combined?
resultant
40
40 How do we describe the forces on an object when the force in one direction is bigger than the force in the other?
unbalanced
41
41 Two forces on an object are in the same direction. How do we calculate the resultant force?
add
42
42 Two forces on an object are in opposite directions. How do we calculate the resultant force?
find the difference between them
43
43 What does the length of a force arrow on a diagram represent?
size of force
44
44 An aeroplane has thrust of 2000N and drag of 1800N. What is the resultant?
200N forwards
45
45 Air resistance on a cyclist is 20N and friction is 5N. What is the total force trying to slow the cyclist down?
25N backwards
46
46 Name a vector quantity that changes as a car drives at constant speed around a roundabout.
velocity
47
47 What are unbalanced forces?
forces of different sizes in opposite directions
48
48 What is the direction of the resultant force on a car that is speeding up?
forwards
49
49 What is the direction of the resultant force on a bicycle that is slowing down?
backwards
50
50 How does a sideways resultant force affect the velocity of a moving object?
changes its direction
51
51 How can the pilot of an aeroplane make the plane gain speed upwards?
increase the lift/upwards force
52
52 How do balanced forces affect the velocity of a moving car?
The car continues with the same velocity.
53
53 You pedal harder on a bicycle. What happens?
you accelerate/get faster
54
54 H What is the name of the force that makes objects move in a circular path?
centripetal
55
55 H What provides the centripetal force for a car going around a roundabout?
friction
56
56 H What are the forces on a moon orbiting around a planet?
gravity acting towards the planet
57
57 H In which direction does centripetal force act?
towards the centre of the circle .
58
58 Why is the force of gravity greater on a lorry than on a car?
larger mass
59
59 Why is the resultant force accelerating a car usually less than the force provided by its engine?
air resistance and/or friction
60
60 Name one force that usually has to be taken into account when working out the resultant force on a moving object
drag or friction
61
61 When will a resultant force act to slow a car down?
when backwards forces are greater than forwards ones
62
62 How can friction act to make a car speed up?
between tyres and road
63
63 How can friction act to make a car slow down?
in brakes
64
64 What is the formula linking force, mass and acceleration?
F = m x a
65
65 An object is moving at a constant velocity. What can you say about the forces on it?
balanced
66
66 What is the equation relating these factors?
speed = distance / time
67
67 What type of force is used to slow down a moving vehicle?
friction
68
68 Where is this force applied?
brakes, tyres
69
69 Why is a wet road more slippery than a dry one?
water acts as lubricant
70
70 An object has a negative acceleration. What does this mean?
it is slowing down
71
71 What effect does drinking alcohol have on human reaction times?
slows them down/makes them longer
72
72 How will being tired affect reaction time?
make it longer
73
73 What does ?braking distance? mean?
the distance a car travels while slowing down
74
74 What does ?thinking distance? mean?
the distance a car travels while the driver is reacting to a danger and deciding to apply the brakes
75
75 How does speed affect the thinking distance?
higher speed, longer thinking distance/thinking distance directly proportional to speed
76
76 How does speed affect the braking distance?
higher speed, longer braking distance/braking distance proportional to speed squared
77
77 How does the force needed for an acceleration depend on the size of the acceleration?
larger acceleration, larger force needed
78
78 What does deceleration mean?
slowing down/a negative acceleration
79
79 H What factors affect the momentum of a moving object?
mass, velocity
80
80 H How does the mass affect momentum?
higher mass, higher momentum
81
81 H How does the velocity affect momentum?
higher velocity, higher momentum
82
82 H What does momentum is conserved mean?
total momentum is the same before and after a collision
83
What is a scalar quantity?
A force with just magnitude
84
What is a vector quantity?
A force with both direction and magnitude
85
Is distance vector or scalar?
Scalar
86
Is mass vector or scalar?
Scalar
87
Is speed vector or scalar?
Scalar
88
Is displacement vector or scalar?
Vector
89
Is weight vector or scalar?
Vector
90
Is velocity vector or scalar?
Vector
91
Is acceleration vector or scalar?
Vector
92
Is force vector or scalar?
Vector
93
Is momentum vector or scalar?
Vector
94
How do you find the gradient of a line on a graph?
Change in y / change in x
95
What does a horizontal line in a velocity/time graph mean?
Moving at a steady speed
96
What does a / line in a velocity/time graph mean?
Acceleration
97
In a velocity/time graph, what is acceleration equal to?
The gradient
98
How do you calculate the gradient in a velocity/time graph?
Change in y / change in x (velocity / time)
99
How do you find distance travelled in a velocity/time graph?
Calculate the area under the graph
100
How do you calculate acceleration from velocities?
Acceleration = _(final velocity - initial velocity)_
time taken
101
final velocity2 - initial velocity2 =
2 x acceleration x distance
102
What is the value of gravity on earth?
10 N/kg
103
Is the value of gravity on earth more or less than the value of gravity on the moon?
Less
104
If you are falling on earth, what is your acceleration due to gravity?
10m/s squared
105
What is the resultant force?
Difference between two forces in different directions - equal to the sum to all forces applied on an object
106
Force =
mass x acceleration
107
Weight =
mass x gravity
108
Your mass never changes but your weight...
will change depending on gravity - ie if you are on a different planet
109
What is centripetal force?
The resultant force when things are moving in a circle
110
Things moving in a circle due to centripetal force have a constant/changing speed and a constant/changing velocity
constant speed, changing velocity
111
When things move in a circle, why does the velocity change?
Velocity is speed in a certain direction
112
Momentum =
mass x velocity
113
What is the law of conservation of momentum?
Momentum is always conserved
114
F = _mv - mu_
?
t
115
Momentum before =
momentum afterwards
116
Stopping distance =
thinking distance + breaking distance
117
The faster you are going, the more the thinking distance and breaking distance increases/decreases
Increases
118
Why does thinking distance increase the faster you are going?
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
Name 2 things that have an effect on thinking distance
Any 2 from alcohol, drugs, tiredness and caffeine
120
Does taking illegal drugs have a positive or negative impact on thinking distance?
Negative
121
Does tiredness have a positive or negative impact on thinking distance?
Negative
122
Does drinking alcohol have a positive or negative impact on thinking distance?
Negative
123
Does caffeine have a positive or negative impact on thinking distance?
Positive
124
Name 2 things that have an effect on breaking distance
Any 2 from the condition of the tyres, the condition of the road and the weight of the car
125
What impact does the condition of tyres have on breaking distance?
New tyres will stop much quicker than old tyres which don't have much grip on the road
126
What impact does the condition of the road have on breaking distance?
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
What impact does the weight of the car have on breaking distance?
A heavier car is gong to take much longer to stop
128
What impact does the weight of the car have on breaking distance?
A heavier car is gong to take much longer to stop
129
What is kinetic energy measured in?
Joules (J)
130
distance =
speed x time
131
kinetic energy =
1/2 x mass x velocity2
132
work done =
force x distance
133
