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*AQA GCSE Physics* > 1. Energy > Flashcards

1. Energy Flashcards

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1
Q

What are the nine types of energy?

A

Kinetic, sound, light, thermal, electrical, gravitational potential, elastic potential (strain), chemical, nuclear

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2
Q

What are the two ways that energy can be transferred?

A

From place to place or from one form into another

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3
Q

What is ‘waste energy’?

A

Energy that is converted to either the wrong place or the wrong form

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4
Q

What is ‘useful energy’?

A

The energy converted to where it is wanted in the form wanted

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5
Q

What is an efficient device?

A

A device where most of the energy is usefully converted

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6
Q

What form is waste energy nearly always in?

A

Heat and sound energy dissipated to the surroundings

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7
Q

What is a closed system?

A

A system where the total energy is always the same. No energy is transferred in or out.

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8
Q

Equation for efficiency?

A

Useful energy given out by device / energy put in x100

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9
Q

What is work done equal to?

A

Energy transferred

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10
Q

Equation for work done?

A

Work done = force x distance in direction of force

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11
Q

What is the rate at which energy is transformed?

A

Power

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12
Q

When is work done?

A

When any object is moved around ie energy is supplied

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13
Q

Equation for power?

A

Power = energy / time taken

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14
Q

What is 1 watt equal to?

A

1 Joule per second

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15
Q

What do you pay for when you pay for electricity?

A

The energy transferred

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16
Q

Equation for kinetic energy?

A

Ek=1/2mv²

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17
Q

Equation for gravitational potential energy?

A

Ep=mgh

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18
Q

How to calculate weight?

A

Mass x gravitational field strength

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19
Q

How to calculate a change in kinetic energy?

A

Ek=1/2mv²-1/2mu²

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20
Q

What is change in kinetic energy equal to?

A

Work done and kinetic energy transferred

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21
Q

Equation for elastic potential energy?

A

Ee=1/2ke²

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22
Q

Why does a compression still act like an extension?

A

The same amount of energy is stored

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23
Q

What is internal energy?

A

The energy stored by the particles of a substance

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24
Q

What is internal energy a sum of?

A

The kinetic energy of all the particles and the potential energy of all the particles due to their relative positions and forces between them

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25
Q

What does internal energy not include?

A

Gravitational potential energy or the kinetic energy caused by motion of the whole substance

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26
Q

What is the average kinetic energy of gas molecules related to?

A

The temperature of a gas

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27
Q

What happens to kinetic energy if the temperature of a substance is increased?

A

The total kinetic energy of the particles increases and so the internal energy increased

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28
Q

What is latent heat and specific latent heat?

A

The energy needed to change the state of a substance without changing the temperature

Specific latent heat refers to 1kg of a substance

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29
Q

What happens to the temperature during change of state?

A

The temperature is constant, so the total kinetic energy of particles does not change

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30
Q

What happens to the energy of particles when a substance melts or boils?

A

The total potential energy of the particles increased because energy is needed to break the bonds

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31
Q

What is happening when a substance is heating?

A
  • temperature increases
  • kinetic energy increases
  • potential energy is constant
  • internal energy increases
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32
Q

What is happening when a substance is changing state?

A
  • temperature is constant
  • kinetic energy is constant
  • potential energy increases
  • internal energy increases
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33
Q

What factors affect how much energy must be gained by an object as its temperature increases?

A
  • temperature increase
  • mass
  • material
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34
Q

What is specific heat capacity?

A

The amount of energy required to raise 1kg of a material by 1c

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35
Q

What is the specific heat capacity of water?

A

4200 J/kg*c

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36
Q

What is the specific heat capacity of copper?

A

390 J/kg*c

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37
Q

What is the equation for specific heat capacity?

A

Specific heat capacity = energy / mass x temperature change

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38
Q

What is latent heat measured in?

A

Joules per kilogram

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39
Q

What is the specific latent heat of fusion (lf)?

A

The energy needed to change state of 1kg of the substance from solid to liquid

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40
Q

What is the specific latent heat of vaporisation (lv)?

A

The energy needed to change the state of 1kg of the substance from liquid to gas

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41
Q

How to work out specific latent heat?

A

Latent heat = energy / mass

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42
Q

What is specific latent heat measured in?

A

J/kg

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43
Q

How can heat be transferred?

A

Conduction, convection and radiation

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44
Q

What direction does thermal energy travel in?

A

Hot to cold

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45
Q

What is conduction?

A

Particles that are very close together can transfer heat energy as they vibrate

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46
Q

Which is the method of heat transfer in solids?

A

Conduction

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47
Q

How do non-metals conduct?

A

As a non-metal is heated at one end, the atoms near the heat source gain kinetic energy and vibrate more and collide with each other so the energy is passed on

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48
Q

How do metal conduct?

A

When a metal is heated, free electrons gain kinetic energy so they move faster and diffuse through the metal - energy is transferred when electrons collide with other electrons or ions

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49
Q

Why is the rate of energy transfer greater in copper than steel?

A

Copper a higher thermal conductivity

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50
Q

What is the best insulator?

A

A vacuum

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51
Q

Why can’t conduction occur in a vacuum?

A

There are no particles to collide and pass on the energy

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52
Q

What do many insulating materials contain?

A

Pockets of trapped air

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53
Q

Why is air a good insulator?

A

It is a gas and particles are too far apart to transfer energy effectively

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54
Q

Why do steel pans have wood or plastic handles?

A

They do not get hot and burn your hand because they are made of material that cannot conduct heat so is an insulator

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55
Q

Why is felt a better insulator than paper?

A

It has air pockets and air is a good insulator as it is a gas

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56
Q

How to test different materials as insulators?

A

Fill 3 containers with boiling water, put a thermometer in each, wrap 3 different types of insulator and the hot water and measure temperature of each container in intervals

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57
Q

Why are wood and fibre glass good insulators?

A

They have trapped air in pockets - air is a gas so a poor conductor

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58
Q

Which are the best insulating materials?

A

The ones with the lowest thermal conductivity

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59
Q

What are fluids?

A

Substances that can flow i.e. Liquids and gases

60
Q

What happens when fluid particles are heated?

A

They move around more and spread out

61
Q

What happens when a fluid is heated?

A

Becomes less dense - same number of particles take up more space

62
Q

How is wind an example of convection?

A

On a beach, the air above sand is heated, becomes less dense and rises. Cold air above the sea is sucked inland as wind

63
Q

How is a freezer an example of convection?

A

A freezer cools air at the top and cools food on the way down. Warmer air at the bottom rises and a convection current is set up inside the fridge

64
Q

Where can’t convection occur?

A
  • in solids because particles are not free to flow

* in vacuums because there are no particles to flow and carry energy

65
Q

How does trapped air reduce heat loss by convection in the home?

A

Convection causes heat to be lost through the roof - loft instillation helps to reduce this. Trapped air in fibre glass is not free to flow so this helps to prevent convection currents

66
Q

Where can energy be lost from in the home?

A

Through the roof, windows, floors, walls, doors and gaps

67
Q

How can energy loss be reduced through the roof?

A

Loft insulation

68
Q

How can energy loss be reduced through walls?

A

Cavity wall insulation

69
Q

How can energy loss be reduced through doors and gaps?

A

Draught excluders

70
Q

How can energy loss be reduced through floors?

A

Carpets

71
Q

How can energy loss be reduced through windows?

A

Curtains and double glazing

72
Q

What type of heat transfer does double glazing reduce?

A

Conduction

73
Q

What type of heat transfer does cavity wall insulation reduce?

A

Conduction and convection

74
Q

What type of heat transfer does loft insulation reduce?

A

Conduction and convection

75
Q

What type of heat transfer does foil behind radiators reduce?

A

Radiation

76
Q

What type of heat transfer does draught excluders reduce?

A

Convection

77
Q

What type of heat transfer do curtains reduce?

A

Convection (and radiation, conduction)

78
Q

What type of heat transfer do carpets reduce?

A

Conduction (and convection)

79
Q

How does double glazing reduce heat transfer?

A

2 layers so it is further for heat to travel

Air between glass which is a gas so a good insults

80
Q

How does cavity wall insulation reduce heat transfer?

A

2 layers so it is further for heat to travel

Air between walls which is a good insulator

Foam which has pockets of air which reduce flow in convection

81
Q

How does loft insulation reduce heat transfer?

A

Fibre glass has pockets of trapped air

82
Q

How does foil behind radiators reduce heat transfer?

A

Silver is a good reflector so heat from back radiator is reflected into room

83
Q

How do draught excluders reduce heat transfer?

A

Close gaps around doors and windows so air cannot flow through

84
Q

How do curtains reduce heat transfer?

A

Block gaps so air cannot flow through

Opaque so heat is not passed through

85
Q

How do carpets reduce heat transfer?

A

Made of insulating materials which have a lot of air between fibres

86
Q

What is payback time?

A

A way to calculate how cost effective types of insulation are. It is the time taken to save the money that it cost to buy

87
Q

How to calculate pay back time?

A

Payback time = cost of insulation/ annual saving

88
Q

What is a renewable energy resource?

A

One that can be replenished as it is used

89
Q

What are some types of renewable energy resources?

A 
Tidal
Solar
Geothermal
Biofuel
Wind
Hydroelectric
Wave
90
Q

How does geothermal power work?

A

Hot rocks underground heat water to produce steam. Holes are drilled down to the hot region, steam comes up and used to drive turbines which drive electric generators

91
Q

Energy transformations in geothermal power?

A

Heat -> Kinetic -> Electrical

92
Q

Where can geothermal power stations be built?

A

Near hot reservoirs beneath the earth’s surface

93
Q

Advantages of geothermal power?

A
  • No pollution
  • Low running costs
  • Don’t take up much room - no impact on environment
94
Q

Disadvantages of geothermal power?

A
  • Difficult to find suitable sites for power stations
  • Rocks have to be certain type and depth
  • Rocks above have to be soft enough to drill through
  • If not carefully managed a borehole can ‘run out of steam’ and not usable for decades
  • Some dangerous gases and minerals come out of boreholes and are hard to dispose of
95
Q

How does wind power work?

A

The wind turns blades which tune a rotor shaft. The resultant mechanical power is used to drive an electricity generator

96
Q

Energy transformations in wind power?

A

Kinetic -> Electrical

97
Q

Where can wind power stations be built?

A

In windy places e.g. the sea

98
Q

Advantages of wind power?

A
  • Dovetails with other systems
  • Simple technology
  • Once constructed, low running costs
  • Occupied land can still be used for farming
  • Cheap electricity
  • Suitable for less sunny regions
  • Safe, if properly maintained
  • Plentiful wind supply
  • No pollution
99
Q

Disadvantages of wind power?

A
  • No wind = no power
  • Wind farms create a constant low level noise
  • Can interfere with TV and radar
  • Aesthetically disturbing
  • Small electricity production from each windmill
100
Q

How does wave power work?

A

Friction develops between air and water as wind blows across the water. Energy is transferred between the two elements. Taking the motion of the waves and translating it to mechanical/electrical energy generates energy from the waves

101
Q

Energy transformations in wave power?

A

Kinetic -> Electrical

102
Q

Where can wave power stations be built?

A

In the sea

103
Q

Advantages of wave power?

A
  • No waste or pollution
  • Wave energy generators can produce large amounts of energy
  • Once constructed, low running costs
104
Q

Disadvantages of wave power?

A
  • Can be noisy
  • Must be able to withstand very rough weather
  • Wave energy generators are only effective when exposed to strong waves
  • May be a hazard to ships and leisure craft
105
Q

How does tidal power work?

A

A bay dammed with gates and turbines fitted along the length of the dam. Gates are opened to let the tide in and turn the turbines to produce electricity

106
Q

Energy transformations in tidal power?

A

Gravitational potential -> Kinetic -> Electric

107
Q

Where can tidal power stations be built?

A

In an estuary

108
Q

Advantages of tidal power?

A
  • Amount of energy produced is predictable
  • Low running costs
  • No waste or pollution
  • Reliable technology
  • No fuel
109
Q

Disadvantages of tidal power?

A
  • Early stages of development
  • Only produced energy for 10 hours a day as tide moves in and out
  • Expensive to install
  • Few suitable places
110
Q

How does biofuel work?

A
  1. Energy crops - plants grown specifically for fuel e.g. wood. Some crops are fermented to produce ethane
  2. Waste - as material rots it gives off methane which is burnt to produce steam and turn a turbine
111
Q

Energy transformations in biofuel?

A

Chemical -> Heat -> Kinetic -> Electrical

112
Q

Where can biofuel power stations be built?

A

Fields or factories - waste underground

113
Q

Advantages of biofuel?

A
  • Fuel is cheap
  • Methane is a greenhouse gas and burning it would reduce the amount in the atmosphere
  • Using waste material makes good environmental and economical sense
114
Q

Disadvantages of biofuel?

A
  • Creating enough waste is difficult
  • CO2 produced by bio-energy production
  • Some waste materials not available all year round
115
Q

How does solar power work?

A

Sonar cells are devices that convert light energy into electrical energy directly.

Sonar water heating uses heat from the sun to heat water in glass panels on a roof. Water is pumped through pipes in the panel.

Sonar furnaces use mirrors to concentrate the sun’s energy and produce high temperatures

116
Q

Energy transformations in solar power?

A

Light -> Electrical

117
Q

Where can solar power stations be built?

A

On roofs

118
Q

Advantages of solar power?

A
  • Safe
  • Can generate energy in remote places
  • Handy for low-power uses like garden lights
  • Once constructed, low running costs
119
Q

Disadvantages of solar power?

A
  • Doesn’t work at night
  • Electricity produced is more expensive
  • Energy has to be stored in batteries, hydrogen or water
  • Can’t be used as the only system in cloudy places
120
Q

How does hydroelectric power work?

A

Flowing waters create energy that can be captured. When demand increases water is released back into a lower reservoir through a turbine. The water comes from behind a dam. The water drives electrical generators which may be built inside the dam

121
Q

Energy transformations in hydroelectric power?

A

Gravitational potential -> Kinetic -> Electrical

122
Q

Where can hydroelectric power stations be built?

A

Upland areas

123
Q

Advantages of hydroelectric power?

A
  • No pollution

* Can produce electricity on demand

124
Q

Disadvantages of hydroelectric power?

A
  • Fish cannot migrate upstream, or downstream to the ocean
  • Can impact water quality and flow
  • Can be impacted by drought
125
Q

What is a fuel?

A

A material that can be burnt to provide energy (light and heat)

126
Q

Energy transformation in a fuel?

A

Chemical -> Light + Heat

127
Q

How does coal form?

A

Coal formed when old plants from millions of years ago died and formed layers at the bottom of swamps, to form peat

128
Q

How do oil and natural gas form?

A

Oil and natural gas are formed when layers of sediment, plants and bacteria become buried and pressure is added over millions of years

129
Q

What are the fossil fuels?

A

Oil, natural gas and coal

130
Q

How do fossil fuels produce electricity?

A

The fuel is burned and heat produced boils water, creating high pressure which turns a turbine. The turbine turns a generator

131
Q

How does natural gas produce electricity?

A

It is burnt and the hot gases produced are used directly to turn a turbine

132
Q

What is the start up time of coal?

A

7 hours

133
Q

What is the start up time of oil?

A

4 hours

134
Q

What is the start up time of natural gas?

A

1 hour

135
Q

How long will coal last?

A

About 300 years

136
Q

How long will oil last?

A

About 45 years

137
Q

How long will gas last?

A

25-30 years

138
Q

Which fossil fuel creates the most pollution?

A

Coal

139
Q

Which fossil fuel creates the least pollution?

A

Natural gas

140
Q

What is the difference between first and second generation biofuels?

A

First generation have been derived from starches, sugars or animal fats

Second generation are derived from more advanced sources and are renewed as part of the carbon cycle

141
Q

What are the different types of biofuels?

A

Bioethanol, biodiesel, biomethane

142
Q

What makes a good insulator?

A

Low thermal conductivity (low energy transfer/ second)

143
Q

What is the relationship between temperature and infrared radiation?

A

Higher temperature= more infrared radiation emitted

144
Q

What is black body radiation?

A

Radiation emitted by a body that absorbs all radiation incident on it

145
Q

Why does the temperature of an object increase?

A

It absorbs more infrared radiation than it emits

*AQA GCSE Physics* (10 decks)

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