Section 1: Motion, Forces & Conservation of Energy Flashcards

1
Q

What is a scalar quantity?

A

A quantity that only has a magnitude but no direction

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2
Q

What is a vector quantity?

A

A quantity that has a magnitude and a direction

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3
Q

What are examples of scalar quantities?

A

Speed
Mass
Distance
Energy

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4
Q

What are examples of vector quantities?

A

Velocity
Displacement
Weight
Force
Acceleration
Momentum

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5
Q

What is distance?

A

How far an object has moved (not including its direction)

SCALAR

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6
Q

What is displacement?

A

The distance and direction in a straight line from an objects starting point to its finishing point

VECTOR

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7
Q

What is speed?

A

How fast your going with no regard to direction

SCALAR

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8
Q

What is velocity?

A

Speed in a certain direction

VECTOR

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9
Q

What is acceleration?

A

The change in velocity in a certain amount of time

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10
Q

What is the acceleration of an object due to gravity close to Earths surface?

A

10m/s^2

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11
Q

What is the typical speed (m/s) of walking?

A

1.4 m/s

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12
Q

What is the typical speed (m/s) of running?

A

3 m/s

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13
Q

What is the typical speed (m/s) of cycling?

A

5.5 m/s

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14
Q

What is the typical speed (m/s) of a car in a built up area?

A

13 m/s

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15
Q

What is the typical speed (m/s) of a car on a motorway?

A

31 m/s

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16
Q

What is the typical speed (m/s) of a train?

A

Up to 55 m/s

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17
Q

What is the typical speed (m/s) of a plane?

A

250 m/s

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18
Q

What is the typical speed (m/s) of wind?

A

5 - 20 m/s

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19
Q

What is the typical speed (m/s) of sound?

A

340 m/s

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20
Q

What does a flat line show on a distance time graph?

A

The object is stationary

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21
Q

What does a steepening curve show on a distance time graph?

A

Object is accelerating

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22
Q

What does a straight line show on a velocity time graph?

A

Object is travelling at a steady speed

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23
Q

What does a curve that’s levelling off show on a distance time graph?

A

Deceleration

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24
Q

What is deceleration?

A

Negative acceleration - shows an object is slowing down

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25
Q

What does a gradient show on a distance time graph?

A

Speed

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26
Q

How to calculate gradient?

A

Rise/run

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27
Q

What does a flat line show on a velocity time graph?

A

The object is travelling at a steady speed

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28
Q

What does an uphill straight line show on a velocity time graph?

A

There is a constant acceleration

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29
Q

What does a steepening curve show on a velocity time graph?

A

Increasing acceleration

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30
Q

What does a downhill straight line show on a velocity time graph?

A

A constant deceleration

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31
Q

What does a gradient show on a velocity time graph?

A

Acceleration

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32
Q

What does the area under the graph show on a velocity time graph?

A

Distance travelled in that given time

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33
Q

What is Newton’s first law?

A

An object remains in the same state of motion unless a resultant force acts on it. If the resultant force on an object is zero, this means:
a stationary object stays stationary
a moving object continues to move at the same velocity (at the same speed and in the same direction)

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34
Q

What is Newton’s second law?

A

Force = mass x acceleration

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35
Q

What is Newton’s third law?

A

If object A exerts a force on object B, object B will exert the same force in the opposite direction onto object A

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36
Q

What happens when a girl pushes on a wall (relate to Newton’s third law)?

A

The wall will push back on the girl with equal and opposite force

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37
Q

What is weight?

A

The force due to gravity

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38
Q

What is weight caused by near Earth?

A

The gravitational field around Earth

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39
Q

What does object weight depend on?

A

Strength of gravitational field at the objects location

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40
Q

What is inertial mass?

A

The measure of how hard it is to change an objects velocity due to its mass
It’s the ratio of force over acceleration: mass = force/acceleration

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41
Q

What happens to velocity when an object travels in a circular motion with constant speed?

A

Has a constantly changing velocity BECAUSE direction constantly changes too

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42
Q

What does a changing velocity mean?

A

The object is accelerating so there’s a resultant force acting on it

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43
Q

What is the force called that’s produced by a circular motion?

A

Centripetal force - acts towards the centre of the circle

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44
Q

What is the correlation between the mass and momentum of an object?

A

The greater an objects mass, the greater its momentum

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45
Q

What is the correlation between the velocity and momentum of an object?

A

The greater an objects velocity, the greater its momentum

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46
Q

What is conservation of momentum?

A

In a closed system, total momentum before an event equals total momentum after an event

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47
Q

How can Newton’s third law be linked with momentum (use example of two balls)?

A
  1. Ball A collides with ball B
  2. Ball A and ball B exert equal and opposite forces on eachother due to Newton’s third law
  3. Due to f=ma, ball A decelerates at the same rate that ball B accelerates
  4. The time the force is applied is the same for both balls, so their change in speed is the same
  5. Momentum is lost by ball A equals momentum gained by ball B. So total momentum before equals total momentum after
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48
Q

What is the typical human reaction time?

A

0.2 - 0.9 s

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49
Q

What are the three factors that affect reaction time?

A

Tiredness
Drugs and alcohol
Distractions

50
Q

What is the process of doing the ruler test?

A
  1. Get someone to hold a ruler so zero is between your thumb and forefinger
  2. Ruler is dropped without warning and catch it as quickly as possible whilst a stopwatch is pressed and stoped when the ruler is caught
  3. Use the distance that the ruler fell to calculate the reaction time
51
Q

What is the stopping distance equation?

A

Stopping distance = thinking distance + braking distance

52
Q

What are the 2 factors that increase thinking distance?

A

Faster vehicle speed
Longer driver reaction times

53
Q

What are the 4 factors that increase braking distance?

A

Faster vehicle speed
Heavier vehicle
Poor, wet or icy road surface
Damaged or worn brakes or tyres

54
Q

What is thinking distance?

A

How far the vehicle moves during the drivers reaction time

55
Q

What is braking distance?

A

The distance taken to stop whilst brakes are applied

56
Q

What happens to thinking distance and braking distance if speed doubles?

A

Thinking distance doubles
Braking distance quadruples

57
Q

What happens for a car to stop?

A

When: work done by brakes = energy in cars kinetic energy store

58
Q

What is a good estimated for a cars mass?

A

1000kg

59
Q

How does a larger braking force impact deceleration? Why?

A

Larger breaking force means a larger deceleration BECAUSE…

the faster a vehicle is going, the greater the braking force needed to make it stop in a certain distance

60
Q

What can large decelerations do to cars and the road?

A

Cars: can cause brakes to overheat
Roads: can cause vehicle to skid - DANGEROUS

61
Q

What are the 8 types of energy store?

A

Kinetic
Gravitational potential
Elastic potential
Electrostatic
Thermal
Chemical
Magnetic
Nuclear

62
Q

What are the 4 types of energy transfer?

A

Mechanical (a force doing work)
Electrical (work done by moving charges)
Heating
Radiation (e.g. light or sound)

63
Q

What is a system?

A

A single object or a group of objects

64
Q

What is conservation of energy?

A

Idea that energy can be transferred usefully, can be stored or dissipated BUT CANNOT be created or destroyed

65
Q

What is a closed system?

A

When no energy (or matter) is transferred in or out of the system, so there is not net change in total energy

66
Q

What are the energy transfers for an arm throwing a ball up?

A

Chemical energy store of the arm —> kinetic energy store of ball and arm

BECAUSE WORK DONE MECHANICALLY BY FORCE EXERTED BY ARM

67
Q

What are the energy transfers for a ball falling?

A

Gravitation potential energy store of ball —> kinetic energy store of the ball

BECAUSE WORK DONE MECHANICALLY BY GRAVITATIONAL FORCE

68
Q

What are the energy transfers for a kettle boiling water?

A

Mains —> thermal energy store of kettles heating element —> thermal energy store of water

BECAUSE ENERGY WAS TRANSFERRED ELECTRICALLY FIRST THEN TRANSFERRED BY HEAT

69
Q

What is the equation for efficiency?

A

Useful energy transferred/total energy supplied

70
Q

Why is no device 100% efficient?

A

In all systems, energy is wasted to a store thats not useful (usually thermal)

71
Q

What does the width of the arrow show in a Sankey diagram?

A

The energy supplied

72
Q

Steps to drawing a Sankey diagram?

A
  1. Create a key
  2. First relate the TOTAL energy supplied to the key and draw that width
  3. Coming horizontally from the total energy line, draw an arrow the size of the USEFUL energy that’s related to the key
  4. Coming vertically from just after the total energy line and just before the useful energy arrow, draw an arrow the size of the WASTED energy that’s related to the key
73
Q

How does lubrication work (process)?

A
  1. The frictional force acts between moving gears, so energy is wasted and dissipated in an unwanted energy transfer
  2. Apply lubricant
  3. Frictional force is reduced so less energy is wasted
74
Q

What does thermal insulation do? How?

A

Reduces unwanted energy transfers by heating an object
E.g. using cotton wool

75
Q

What do lubrication and thermal insulation essentially do to efficiency?

A

Increase efficiency of useful energy transfers

76
Q

What are the two ways to decrease how quickly a building cools?

A
  1. Increase thickness of its walls
  2. Make walls out of material with lower thermal conductivity
77
Q

What is conduction?

A

Where vibrating particles transfer energy to neighbouring particles

78
Q

What is the correlation between a materials thermal conductivity and the rate at which energy transfers by conduction?

A

The higher a materials thermal conductivity, the faster it transfers energy by conduction

79
Q

What are the ways to reduce energy loss?

A

Lubricaiton
Thermal insulation
Double glazed windows

80
Q

What is a non renewable energy resource?

A

Energy resources that will run out one day

81
Q

What is a renewable energy resource?

A

Energy resources that will never run out

82
Q

What are the 3 examples of fossil fuels?

A

Coal
Oil
Gas

83
Q

What is oil used for?

A

To make fuel (petrol and diesel) for cars

84
Q

What is coal used for?

A

Powering steam trains
Heating

85
Q

What is gas used for?

A

Used to heat homes and cook food

86
Q

What does the combustion of fossil fuels generate?

A

Generate electricity

87
Q

What are disadvantages of fossil fuels?

A

Release CO2 when they’re burnt - contributes to global warming
When coal and oil are burnt, they release sulfur dioxide - causes acid rain

88
Q

What are the 2 types of non renewable energy resources?

A
  1. Fossil fuels
  2. Nuclear power
89
Q

How does nuclear power generate electricity?

A

The nuclear fuel undergoes fission in nuclear reactors - generates electricity

90
Q

What are disadvantages of nuclear power?

A

Nuclear waste is dangerous and difficult to dispose of
Carries risk to a major catastrophe e.g. Chernobyl

91
Q

What are the 5 examples of renewable energy resources?

A
  1. Tidal power
  2. Solar power
  3. Wind power
  4. Bio-fuels
  5. Hydroelectric power
92
Q

How is electricity generated by tidal power?

A
  1. The tide comes in
  2. Water builds up behind a dam
  3. The water that’s built up is allowed out through turbines
  4. These turbines produce electricity
93
Q

What is a tidal barrage?

A

A big dam built across river estuaries

94
Q

What are advantages of tidal power?

A

No pollution is produced

95
Q

What are disadvantages of tidal power?

A

Disturb habitats of nearby wildlife
Spoil the view
Dams are expensive to build

96
Q

How is electricity generated through solar power?

A

Solar panels generate electricity when the sun directly hits them

97
Q

What are advantages of solar power?

A

No pollution produced

98
Q

What are disadvantages of solar power?

A

Don’t work well in the winter or when there’s no sun

99
Q

What is solar power also used for (not to generate electricity)?

A

To heat water which is pumped into radiators - heat homes

100
Q

How is electricity generated through wind power?

A

Wind turns wind turbines - generates electricity

101
Q

What are advantages of wind power?

A

No pollution produced

102
Q

What are disadvantages of wind power?

A

Noisy
Spoil the view
Unreliable if there’s no or little wind

103
Q

How is electricity generated by bio fuels?

A

Bio fuels are burned - generates electricity

104
Q

What are bio fuels made of?

A

Plant products or animal dung

105
Q

What are disadvantages of biofuels?

A

Large areas of forest are sometimes destroyed to grow bio fuels - species lose habitats

106
Q

How is electricity generated by hydroelectric power?

A
  1. Big dams are built
  2. A valley then fills up with water
  3. The water is then allowed out of the dam through turbines
  4. This generates electricity
107
Q

What are advantages of hydroelectric power?

A

No pollution produced

108
Q

What are disadvantages of hydroelectric power?

A

Dams are expensive to build and take up a large area to build
If the valley floods, it can have an impact on habitats and the overall environment

109
Q

What happened to the demand for electricity in the years 1900-2000? Why?

A

It increased BECAUSE… population grew & people began to use electricity for more things

110
Q

What happened to the demand for electricity in the years 2000 onwards? Why?

A

It’s decreasing BECAUSE… appliances are more efficient & people are more careful with the amount of energy they use up

111
Q

What are 3 reasons why renewable energy resources are increasing?

A
  1. Burning fossil fuels is very damaging to environment - we have discovered this
  2. We need to learn how to get by without non renewables as they’ll run out (finite)
  3. There’s pressure on governments and companies to introduce more renewable energy resources
112
Q

What are the advantages to changing to renewable energy resources?

A

Less or no pollution produced
They won’t run out
Better for the environment

113
Q

What are the disadvantages to changing to renewable energy resources?

A

They’re expensive
Sometimes they’re unreliable - e.g. if there’s no sun, wind, or rain

114
Q

What are 3 examples of scalar-vector pairs?

A
  1. Speed and velocity
  2. Distance and displacement
  3. Mass and weight
115
Q

CORE PRACTICAL: What are all of the components of the equipment used to test the equation F=ma?

A

Trolley on a ramp that’s attached to a string that’s on a pulley
Masses
Stop clock
Metre rule

116
Q

CORE PRACTICAL: How to investigate the effect of mass on acceleration using the trolley experiment?

A
  1. Get a ramp with a starting line and a finish line, place the trolley behind the line and attach string to it
  2. Attach the string to a pulley and to the end of the string, add on a hanging mass that’s on a hook
  3. Once all apparatus is set up, release the trolley from the starting line and start the stop clock
  4. When the trolley passes the finish line, stop the stop clock
  5. Calculate the acceleration by using the equation: acceleration = distancex2/time²
  6. Repeat these steps, each time add another 100g mass to the trolley, until all masses have been added
117
Q

CORE PRACTICAL: What is the control, independent and dependent variable in the trolley experiment used to investigate the effect of mass on acceleration?

A

Control: force (weight)
Independent: mass
Dependent: acceleration

118
Q

CORE PRACTICAL: How to investigate the effect of force on acceleration using the trolley experiment?

A
  1. Get a ramp with a starting line and a finish line, place the trolley behind the line and attach string (attached to a hook) to it which is attached to a pulley
  2. Start with all of the unit masses on the trolley
  3. Once all apparatus is set up, release the trolley from the starting line and start the stop clock
  4. When the trolley passes the finish line, stop the stop clock
  5. Calculate the acceleration by using the equation: acceleration = distancex2/time²
  6. Then move a mass from the trolley to the hook and repeat steps 3-5 until all masses have been added
119
Q

CORE PRACTICAL: What is the control, independent and dependent variable in the trolley experiment used to investigate the effect of force on acceleration?

A

Control: mass
Independent: force (weight)
Dependent: acceleration

120
Q

CORE PRACTICAL: Conclusion - what’s the effect of mass on acceleration?

A

Increasing mass decreases acceleration

121
Q

CORE PRACTICAL: Conclusion - what’s the effect of force on acceleration?

A

Increasing force applied to the trolley increases acceleration