Forces & Motion Flashcards

1
Q

What are scalars?

A

Numbers that only have size

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2
Q

What are 3 examples of scalars?

A
  1. Time
  2. Distance
  3. Speed
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3
Q

How do you calculate speed?

A

Speed = Distance
โ€”โ€”โ€”โ€”โ€”
Time

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4
Q

What are vectors?

A

Numbers that have size AND direction

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5
Q

What are some examples of vectors?

A
  1. Displacement
  2. Velocity
  3. Forces
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6
Q

How do you calculate velocity?

A

Displacement
โ€”โ€”โ€”โ€”โ€”โ€”โ€”
Time

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7
Q

Which changes:
Mass or weight?

A

Weight

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8
Q

Why does weight change?

A

Depending of the gravitational force/ field strength/ pull

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9
Q

What is displacement?

A

The distance covered in a straight line and has a direction

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10
Q

If cyclists maintain the same speed around a bend in the road, does the velocity stay the same?
Give a reason for your answer

A

No, the velocity will change
Because velocity is speed in a certain direction and as the cyclists go around the bend in the road they are changing both direction and therefore velocity

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11
Q

What do you measure weight in?

A

Newtons

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12
Q

What is mass measured in?

A

kg

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13
Q

Nano

A

1 X 10*-9

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14
Q

Micro

A

1 X 10*-6

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15
Q

Milli

A

1 X 10*-3

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16
Q

Kilo

A

1 X 10*3

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17
Q

Mega

A

1 X 10*6

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18
Q

Giga

A

1 X 10*9

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19
Q

Nano unit

A

n

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20
Q

Micro unit

A

u
l

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21
Q

Milli unit

A

m

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22
Q

Kilo unit

A

k

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23
Q

Mega unit

A

M

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24
Q

Giga unit

A

G

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25
Q

1cm =โ€ฆm

A

0.01m

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26
Q

KE=

A

1/2 x m x v*2

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27
Q

GPE=

A

m x g x h

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28
Q

Independent variable

A

What you can change

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29
Q

Dependant variable

A

What you measure as a result of

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30
Q

Control variable

A

Any you keep the same

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31
Q

Repeats in experiments allow you to โ€ฆ (3)

A

Spot anomalies
Take a mean
So you can get more accurate results

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32
Q

What is a method?

A

A step by step guide of what to do to get good results. It must include VARIABLES, EQUIPMENT & PROCEDURE

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33
Q

Speed

A

= Distance/time

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34
Q

Acceleration =

A

Change in velocity/time

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35
Q

unit speed

A

m/s

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36
Q

unit for acceleration

A

m/s*2

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37
Q

Gradient of a distance-time graph

A

Speed

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38
Q

Gradient of a velocity-time graph

A

Acceleration

39
Q

Area under the line on a velocity time graph

A

Distance

40
Q

Earths acceleration due to gravity =

A

G= 10 m/s*2

41
Q

Walking pace

A

1-2m/s

42
Q

Running pace

A

5-8 m/s

43
Q

What is the method for working out distance gone on a velocity time graph?

A

Area under the line

44
Q

Efficiency =

A

Useful energy out/ total energy in

45
Q

How can you work out the acceleration of gravity due to earth?

A

Drop weighted card from a certain point through a light gate to measure velocity

46
Q

V =

A

Final velocity in m/s

47
Q

U =

A

Initial velocity in m/s

48
Q

x =

A

Distance travelled in m

49
Q

Acceleration is

A

A measure of how fast velocity is changing

50
Q

Speed is also known as

A

Velocity

51
Q

What must be done to calculate speed at a driven time from a distance time graph for an accelerating object?

A

Draw a tangent to the curve at the required time
Calculate the gradient of the tangent

52
Q

Give an equation relating final velocity with initial velocity, displacement and acceleration

A

V2=u2+ 2as

53
Q

State a typical value for the speed of sound

A

330 m/s

54
Q

What is the name given to the single force that is equivalent to all the other forces on a given object?

A

The resultant force

55
Q

State Newtonโ€™s first law for a stationary object

A

If the resultant force on a stationary object is zero, the object will remain at rest

56
Q

State Newtonโ€™s first law for a moving object

A

If the resultant force on a moving object is zero, the object will remain at a constant velocity (same speed in sma edirection)

57
Q

State the defining equation for Newtons Second Law

A

Resultant force = mass X acceleration

58
Q

State Newtonโ€™s second law in words

A

An objects acceleration is directly proportional to the resultant force acting on it and inversely proportional to its mass

59
Q

What piece of equipment can be used to measure an objects weight?

A

A calibrated spring-balance or newton-meter

60
Q

What is the resultant force that acts on an object moving in a circle called and in which direction does it act?

A

Centripetal force and acts towards the centre of the circle

61
Q

What is inertial mass?

A

A measure of how difficult it is to change a given objects velocity
The ration of force over acceleration

62
Q

State Newtons Third Law

A

whenever two objects interact, the forces that they expert on each other are always equal and opposite

63
Q

State the equation used to calculate an objects momentum

A

Momentum = mass x velocity

64
Q

What is the unit used for momentum ?

A

kgm/s
kilogram metres per second

65
Q

In a closed system, what can be said about the momentum before and after a collision?

A

The total momentum before and after are equal

66
Q

State an equation linking change in momentum, force and time

A

Force x time = change in momentum

67
Q

How can you measure human reaction times?

A

Using a ruler drop test

68
Q

What is the stopping distance of a vehicle equal to?

A

The sun of thinking distance and braking distance

69
Q

For a given braking distance, if the vehicles speed is increased what can be said about its stopping distance?

A

The stopping distance is increases with an increase in speed.

70
Q

Give a typical range of values for human reaction time

A

0.2 -0.9 seconds

71
Q

Give 3 factors which can affect a drivers reaction time

A
  1. Tiredness
  2. Drugs
  3. Alcohol
72
Q

Give 2 factors which may affect braking distance

A
  1. Adverse (wet/icy) road conditions
  2. Poor tyre/ brake conditions
73
Q

Describe the energy transfers that take place when a car applies its brakes

A

Work is done by the friction force between the brakes and wheel
Kinetic energy of the wheel is converted to heat and is dissipated to the surroundings through the brake discs

74
Q

To stop a car in given distance, if its velocity is increased, what must happen to the braking force applied?

A

The braking force must also be increased

75
Q

State 2 consequences of a vehicle undergoing very large decelerations

A
  1. Kinetic energy converted to heat is very high causing brakes to overheat
  2. Loss of control of the vehicle
76
Q

What is momentum?

A

A measure of how difficult an object is to stop- it is the product of the mass and velocity of a body.

77
Q

What is the momentum equation?

A

Momentum = mass X velocity
p=mxv

78
Q

What are the momentum units?

A

kgm/s

79
Q

Is momentum a scalar or vector quantity?

A

Vector

80
Q

What is the conservation of momentum?

A

The total momentum before is equal to the total momentum after

81
Q

In a collision, momentum is..

A

Passed between objects- it is a conserved quantity

82
Q

What are the 3 types of collision?

A
  1. Explosion
  2. Elastic
  3. Inelastic
83
Q

The more time an impact takesโ€ฆ

A

The less force is exerted

84
Q

Force =

A

Change in momentum / time

85
Q

What is stopping distance?

A

The distance required to bring a car to a halt. It is split into thinking and braking distance

86
Q

Stopping distance =

A

Thinking distance + Braking Distance

87
Q

What is thinking distance?

A

The distance travelled during drivers reaction time

88
Q

What affects thinking distance?

A

Alcohol/drugs
Tiredness
Mobile phone
Distraction
Eating/drinking
Age

89
Q

What is braking distance?

A

The distance travelled once the brakes have been applied

90
Q

What affects braking distance?

A

Speed
Icy roads
Poor tyres
Wet road
Speed
Mass
Car conditions
Worn brakes

91
Q

State what is meant by an elastic collision:

A

Momentum and kinetic energy are conserved

92
Q

State what is meant by an inelastic collision:

A

Momentum is conserved, kinetic energy is not.

93
Q

In an explosion, the momentum must equalโ€ฆ

A

0

94
Q

On a V-T graph, what does positive velocity and negative velocity mean?

A

Since velocity is a vector quantity, positive and negative velocity refer to direction.