# Topic 1 - Energy Flashcards

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1
Q

What is a system?

A

A system is an object or group of objects.

2
Q

What is a kinetic store?

A

The energy stored in an object’s movement.

3
Q

What is a gravitational potential store?

A

The energy stored in objects raised above the Earth’s surface.

4
Q

What is a chemical store?

A

The energy stored by the chemical bonds between atoms.

5
Q

What is an elastic store?

A

The energy stored when an object is being stretched, compressed or squashed.

6
Q

What is a nuclear store?

A

The energy stored in the nucleus of an atom. This energy can be released by radioactive decay.

7
Q

What is an internal store?

A

The internal store of energy is the sum of kinetic energy stored in the particles of an object and the potential energy stored in chemical bonds between particles in the object. It is basically the energy stored by the particles that make up an object.

8
Q

What is the temperature of a body a measure of?

A

The energy in the kinetic stores of its particles.

9
Q

What happens to the energy stores if the temperature of the body increases?

A

The energy in the kinetic stores of the body’s particles increases, which means that the energy in the body’s internal store also increases.

10
Q

What are the components of an object’s internal store?

A

The potential store and the kinetic store.

11
Q

What happens when you eat food with energy?

A

Energy is added to your body’s chemical store. It is stored there until you need it.

12
Q

What happens in order to allow an animal to move.

A

Energy stored in the chemical store, is transferred from it to the kinetic store.

13
Q

What happens in order to make the body warm?

A

Energy stored in the chemical store, is transferred from it to the thermal store.

14
Q

What is the formula for kinetic energy stored?

A

(Ek) = 1/2mv^2 - this is the same as Kinetic Energy Stored = 1/2 x mass x velocity^2 (squared).

15
Q

What are the units for the formula of kinetic energy stored?

A

Joules (J) = 1/2 x Mass (kg) x Velocity^2 (m/s)

16
Q

What is the formula for gravitational potential energy stored?

A

Δ(Ep) = mgΔh - this is the same as Change in Gravitational Potential Energy = mass x gravitational field strength x change in height.

17
Q

What are the units for the formula of gravitational potential energy stored?

A

Joules (J) = Mass (kg) x GFS (n/kg) x Change in height (m)

18
Q

What is the formula for elastic potential energy stored?

A

(Ee) = 1/2ke^2 = this is the same as Elastic Potential Energy Stored = 1/2 x spring constant x extension^2 (squared).

19
Q

What are the units for the formula for elastic potential energy stored?

A

Joules (J) = 1/2 x Spring Constant (N/m) x Extension^2 (m)

20
Q

What is the principle of the conservation of energy?

A

Energy cannot be created or destroyed. It can only be transferred from one store of energy into another.

21
Q

How can electrical work transfer energy?

A

An electrical current transfers energy from one object to another, such as a battery powering a torch.

22
Q

How can mechanical work transfer energy?

A

When energy is transferred from one object to another via a force.

23
Q

How can mechanical work transfer energy when an object falls from a builiding?

A

The weight does mechanical work to transfer energy from the gravitational potential energy store to the kinetic store.

24
Q

What happens with energy when a wheelchair is pushed?

A

Energy is transferred to the kinetic store of the wheelchair.

25
Q

How can heating transfer energy?

A

Heating an object transfers energy to its internal store.

26
Q

How can waves transfer energy?

A

Light and other types of waves can transfer energy to another.

27
Q

Explain fully how a moving object hitting an obstacle transfers energy?

A

The object’s energy is in the kinetic store to begin with because it is moving. When the object collides with the obstacle, energy is converted to: the kinetic store of the obstacle (making it move) and the thermal store of the object and the obstacle (the particles in the object and the obstacle vibrate more). Some energy remains in the object’s kinetic store as it moves away after the collision.

28
Q

How does boiling water in an electric kettle transfer energy?

A

Energy transfers from the electrical store of the mains power supply to the thermal store of the water.

29
Q

How do objects accelerated by constant force transfer energy?

A

Work is done by a force on an object. This work is converted to the object’s kinetic store.

30
Q

How does a vehicle slowing down transfer energy?

A

Starting off, the vehicle’s energy is in the kinetic store. The brakes do work slowing the car down. During this process, energy is lost through heat and sound.

31
Q

How does an object being project upwards transfer energy?

A

The object’s energy is initially in the kinetic store as it moves upwards. The objects energy is slowly transferred into from the kinetic store to the gravitational potential store as it slows down and climbs higher. Once the object reaches its highest point, all of its energy is in the gravitational potential store. As the object falls again, energy transfers from the gravitational potential store to the kinetic store.

32
Q

What is work done by a force?

A

Work done by a force is equal to the energy transferred to the object.

33
Q

How is more work done?

A

Push with the same force for a longer distance, or push with a larger force for the same distance.

34
Q

What is the formula for work done?

A

Work done = force x distance.

35
Q

What are the units for the formula of work done?

A

Joules (J) = Newtons (N) x Distance (m)

36
Q

What is the formula for work done when a current flows?

A

E = V x I x t - this is the same as energy = potential difference x current x time.

37
Q

What is the formula for electrical energy?

A

E = Q x V - this is the same as electrical energy = charge x potential difference.

38
Q

What is the formula for power?

A

Power = work done / time

39
Q

What is the unit for power?

A

Power is measured in Watts (W).

40
Q

What is power?

A

Power is the rate of energy transfer.

41
Q

What is wasted energy?

A

Wasted energy happens when one store of energy is transferred to another, some energy is wasted, this dissipates (spreads out) to anything nearby.

42
Q

What happens to energy when friction occurs?

A

Frictions creates heat energy and this energy is often wasted.

43
Q

What happens to heat and sound energy in car engines?

A

Engines make a lot of noise and get hot when they are being used to move you about. The useful energy store here is the kinetic store because you want the car to move you from one place to another. The heat and sound energy are wasted energy because they are of no use to you.

44
Q

What happens to heat energy in wires?

A

When wires are used in an electrical current, they heat up. This is often not useful energy and they are wasted.

45
Q

What is the formula for efficiency for efficiency of energy transfer?

A

Efficiency of energy transfer = useful energy output / total energy input x 100.

46
Q

What can efficiency never be greater than?

A

It can never be greater than 100%.

47
Q

What are the useful power output and total power input measured in?

A

They are both measured in Watts (W).

48
Q

What are the useful energy output and total energy input measured in?

A

They are both measured in Joules (J).

49
Q

How does lubrication reduce amount of energy wasted?

A

Lubrication reduces frictional forces. A moving object normally at least one frictional force acting against it. This causes some energy to be dissipated. Lubricants can reduce the friction between the surfaces of objects that are rubbing together. They are normally liquids.

50
Q

How does thermal insulation reduce amount of energy wasted?

A

Heat will be lost through the roof, windows, walls and floor. The reduce the energy transfer, we could: fit loft insulation (the roof), use double glazing (windows), use cavity wall insulation (walls) and fit carpets on the floors.

51
Q

How do walls in homes reduce amount of energy wasted?

A

You can decrease the rate a house cools down by: having thicker walls and having walls made from a material with a lower thermal conductivity. The more heat that a material conducts, the higher the rate of energy transfer by conduction across a material.

52
Q

What is an energy resource used for?

A

It is used to generate electricity and other useful forms of energy.

53
Q

How does an energy resource generate electricity?

A

An energy resource is used to rotate a turbine, then the rotating turbine rotates a coil of wire in a magnetic field (a generator), finally the coil of wire creates an electric current. The electric current is an energy carrier that can take the energy to your home.

54
Q

What are fossil fuels used for?

A

Fossil fuels (such as coal and oil) are burnt, to heat a fluid (water), which creates steam and turns a turbine. The turbine rotates, which turns a generator.

55
Q

What are the advantages of fossil fuels?

A

Reliable, on demand electricity.

56
Q

What are the disadvantages of fossil fuels?

A

Non-renewable, inefficient and contributes to global warming.

57
Q

What are the advantages of geothermal energy?

A

Renewable and reliable.

58
Q

What are the disadvantages of geothermal energy?

A

Can only be used where there is volcanic activity close to the surface.

59
Q

What is geothermal energy?

A

In volcanic places, magma (underground lava) has lots of internal energy, the magma heats rocks, which heat water in pipes, this rotates a turbine, which turns a generator.

60
Q

What are the 7 energy resources?

A

Geothermal, solar, nuclear, tidal, water/hydroelectric, wind and fossil fuels.

61
Q

What is wind power?

A

When the wind blows, it rotates a wind turbine, which can turn a generator.

62
Q

What are the advantages of wind power?

A

Source of renewable energy.

63
Q

What are the disadvantages of wind power?

A

Unreliable, only produces power when the wind blows.

64
Q

What is water/hydroelectric power?

A

Water high above the ground is a store of gravitational potential energy. Hydroelectric dams trap water and allowing it to fall rotates a turbine, which turns a generator.

65
Q

What are the advantages of water/hydroelectric power?

A

Renewable and more reliable than wind and solar.

66
Q

What are the disadvantages of water/hydroelectric power?

A

Hydroelectric dams often change the paths of rivers, which can move people out of houses and harm local wildlife.

67
Q

What is tidal energy?

A

The waves and tides in the sea are stores of kinetic energy. Tidal and wave power use this kinetic energy to rotate a turbine, which turns a generator.

68
Q

What are the advantages of tidal energy?

A

Renewable source of energy.

69
Q

What are the disadvantages of tidal energy?

A

The creation of tidal turbines can damage ecosystems in estuaries.

70
Q

What is nuclear energy?

A

In a nuclear reactor, the energy stored in an atoms’ nuclei is released as kinetic energy. Some of this kinetic energy heats up graphite which then heats up a fluid (like water). This creates steam and rotates a turbine, which turns a generator.

71
Q

What are the advantages of nuclear energy?

A

No greenhouse gas emission, so no contribution to global warming and reliable, on-demand electricity.

72
Q

What are the disadvantages of nuclear energy?

A

Disposal of nuclear waste with a very long half-life.

73
Q

What is solar energy?

A

The electromagnetic waves emitted by the sun, transfer energy to the earth. Solar cells absorb these waves and create an electric current without a generator. Some solar cells use heat from the sun to boil water, create steam and rotate a turbine, which turns a generator.

74
Q

What are the advantages of solar energy?

A

Renewable.

75
Q

What are the disadvantages of solar energy?

A

Only produces electricity when there is sunlight.

76
Q

How is the Sun the source of energy for solar power?

A

Solar power comes directly from the Sun.

77
Q

How is the Sun the source of energy for wind power?

A

Winds are created by differences in air pressure. Differences in air pressure arise because of air being unevenly heated by the Sun.

78
Q

How is the Sun the source of energy for wave energy?

A

Waves are created by winds, which are created by the Sun.

79
Q

How is the Sun the source of energy for fossil fuels?

A

Fossil fuels are made of decayed plants and animals, which originally got their energy from the Sun.

80
Q

How is the Sun the source of energy for hydroelectricity?

A

Hydroelectric power is produced by dams. Water builds up behind the dam due to rain, which is produced by the water cycle, which is driven by the Sun or pumped up using electricity from other sources.

81
Q

What are non-renewable resources?

A

They will run out one day.

82
Q

What are renewable resources?

A

They will never run out, they can be or are being replenished as they are used.

83
Q

What are the non-renewable forms of transport?

A

Petrol and diesel vehicles use fuel from oil, and some steam trains use coal for boiling water to produce steam.

84
Q

What are the renewable forms of transport?

A

Bio-fuels power some vehicles.

85
Q

What are the non-renewable forms of heating?

A

Natural gas is used to heat homes, and coal is burnt in fireplaces.

86
Q

What are the renewable forms of heating?

A

Some buildings are heated by geothermal heat pumps, these use geothermal energy resources, and solar water heaters use energy from the sun to heat water.

87
Q

How did the use of electricity change in the 20th century?

A

Electricity use increased because the population of the UK grew bigger.

88
Q

How did the use of electricity change in the 21th century?

A

Electricity use has been decreasing in the UK. This is because appliances are becoming more efficient. People are also becoming more concerned with how much energy they are using at home.

89
Q

What does the UK hope for in terms of energy resources for itself?

A

By 2020, the UK hopes to use renewable energy to provide 15% of its total annual energy. People are becoming more aware of how damaging fossil fuels are to the environment.

90
Q

Why are power plants being built?

A

Energy providers are building power plants that use renewable resources.

91
Q

What type of cars are being produced?

A

Vehicle maker are creating more and more electric cars.

92
Q

What is happening to government policy due to public pressure?

A

Targets for renewable energy source are being introduced.

93
Q

What are limits to renewable energy resources?

A

Reliability - some are less reliable than fossil fuels.
Cost - building renewable power plants is expensive, renewable options (electric cars) are also expensive.
Politics - some politicians may be less keen on renewable energy resources than others.