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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 transferred to either the wrong place or the wrong form- dissipates to the surroundings

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4
Q

What is ‘useful energy’?

A

The energy transferred to where it is wanted in the desired form

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5
Q

What is an efficient device?

A

A device where most of the energy is usefully transferred

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6
Q

What form is waste energy nearly always in?

A

Heat energy given to the surroundings

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7
Q

Equation for efficiency?

A

Efficiency = Useful power output ÷ Total power input

equation works with energy as well

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8
Q

What is work done equal to?

A

Energy transferred

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9
Q

Equation for work done?

A

Work done = force x distance

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10
Q

What is the rate at which energy is transferred?

(Amount of energy transferred per second)

A

Power

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11
Q

When is work done?

A

When a force causes an object to move

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12
Q

Equation for power?

A

Power = energy / time taken

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13
Q

What is 1 watt equal to?

A

1 Joule per second

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14
Q

What do you pay for when you pay for electricity?

A

The energy transferred

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15
Q

Equation for kinetic energy?

A

KE=1/2mv²

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16
Q

Equation for gravitational potential energy?

A

GPE = mgh

m = mass
g = gravitational field strength
h = height

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17
Q

How to calculate weight?

A

weight = mass x gravitational field strength

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18
Q

How to calculate a change in kinetic energy?

A

KE = 1/2mv² - 1/2mu²

KE = final KE - initial KE

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19
Q

What is change in kinetic energy equal to?

A

Work done and kinetic energy transferred

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20
Q

Equation for elastic potential energy?

A

EPE = 1/2ke²

k = spring constant
e = extension

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21
Q

Why does a compression still act like an extension?

A

The same amount of energy is stored

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22
Q

What is internal energy?

A

The energy stored by the particles of a substance

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23
Q

What is internal energy a sum of?

A

The kinetic energy of all the particles due to their individual motions relative to each other and the potential energy of all the particles due to their individual positions relative to each other.

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24
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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25
Q

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

A

The temperature of a gas

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26
Q

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

(discuss internal energy)

A

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

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27
Q

What is latent heat?

A

The energy transferred to or from a substance when it changes state

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28
Q

What happens to the temperature during change of state?

discuss kinetic energy

A

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

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29
Q

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

A

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

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30
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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31
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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32
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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33
Q

What is specific heat capacity?

A

The amount of energy required to raise the temperature of 1kg of a substance by 1 degree celcius

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34
Q

What is the specific heat capacity of water?

A

4200 J/kg*c

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35
Q

What is the specific heat capacity of copper?

A

390 J/kg*c

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36
Q

What is the equation for specific heat capacity?

A

Specific heat capacity = energy / mass x temperature change

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37
Q

Why is the filling of a pie hotter than the crust?

A

The pastry and filling have the same temperature however the filling contains water and has a higher specific heat capacity so transfers more heat energy

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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 required to change state of 1kg of a substance from solid to liquid without changing its temperature.

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40
Q

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

A

The energy required to change the state of 1kg of a substance from liquid to gas without changing its temperature.

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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 heat?

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 heat?

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 (wood and plastic are insulators)

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55
Q

Why is felt a better insulator than paper?

A

Felt has air spaces and air is a good insulator because 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 around them. Measure temperature of each beaker in intervals

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57
Q

Why are wood and fibre glass good insulators?

A

They have trapped air and since air is a gas, it is a poor conductor of heat, thus being insulators

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58
Q

Which are the best insulating materials?

A

The ones with the lowest thermal conductivity

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?

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 and convection

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. Air is a gas therefore a good insulator meaning heat transfer is reduced

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 is a system?

A

A system is an object or
group of objects
that interact

143
Q
A

AQA GCSE Physics (10 decks)

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