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AQA GCSE Physics Higher (Triple) > Unit 1 - Energy > Flashcards

Unit 1 - Energy Flashcards

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1
Q

What is a system

A

A system is defined as:

An object or group of objects

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2
Q

Give an Example of a system

A

An apple sitting on a table is a “system”

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3
Q

When is a system in Equilibrium?

A

When a system is in equilibrium, nothing changes and so nothing happens.

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4
Q

When is there a change in a system?

A

When there is a change in a system, things happen, and when things happen energy is transferred

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5
Q

Energy is measured in a unit of:

A

Joules (J)

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6
Q

What is an open system?

A

An open system allows the exchange of energy and matter to or from its surroundings.

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7
Q

What is an isolated system?

A

An isolated system does not allow the transfer of matter or energy to or from its surroundings.

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8
Q

What is a closed system?

A

A closed system can exchange energy, but not matter to or from its surroundings.

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9
Q

State the principle of conservation of energy?

A

Energy can not be created or destroyed, it can only be transferred from one store to another.

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10
Q

In a closed system, the total amount of energy is:

A

Constant

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11
Q

What is Kinetic energy?

A

Moving objects have energy in their kinetic store.

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12
Q

What is gravitational energy?

A

Objects gain energy in their gravitational potential store when they are lifted above the ground.

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13
Q

What is Elastic energy?

A

Objects have energy in their elastic potential store if they are stretched, compressed, or twisted.

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14
Q

What is electrostatic energy?

A

Objects with electrostatic charge, like electrons and protons, interacting with each other, have energy in their electrostatic store.

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15
Q

What is magnetic energy?

A

Magnets interacting with each other have energy in their magnetic store.

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16
Q

What is Chemical energy?

A

Objects with energy in their chemical store can release energy in chemical reactions.

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17
Q

What is nuclear energy?

A

Atomic nuclei release energy from their nuclear store during nuclear reactions

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18
Q

What is thermal energy?

A

All objects have energy in their thermal store, the hotter the object, the more energy it has in the store.

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19
Q

What is Mechanical working?

A

When a force acts on an object e.g. pulling, pushing, stretching, squashing.

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20
Q

What is electrical working?

A

A charge (Current) moving through a potential difference, e.g. charge flowing around a circuit.

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21
Q

What is heating by particles?

A

Energy is transferred from a hotter object to a colder one.

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22
Q

What is heating by radiation?

A

Energy transferred by electromagnetic waves e.g. Light.

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23
Q

An example of an energy transfer is a hot coffee heating up cold hands?`

A

The System is the Coffee, the mug, and the hand.

Energy is transferred by heating from the thermal store of the coffee to the thermal store of the mug.

Energy is transferred by heating from the thermal store of the mug, to the thermal store of the hand.

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24
Q

When an object is projected upwards, what are the changes in energy stores?

A

The Kinetic energy of the ball is transferred the the GPE store of the ball.

This causes the ball to decelerate

When the ball reaches its maximum height, its Kinetic energy store is empty, and the GPE store is at its highest.

The GPE of the ball is transferred to the Kinetic energy of the ball as it falls.

This causes the ball to accelerate.

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25
Q

When a vehicle slows down, what are the changes in energy store?

A

When a vehicle is moving, it has energy it its kinetic store.

As it slows down or decelerates, energy is transferred to the thermal energy store of its surroundings.

This energy is transferred by heating due to friction between the tyres on the ground, and due to friction between the brakes and brake pads.

Energy is also transferred by heating as the sound waves transfer energy away from the system. (Making the air particles vibrate)

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26
Q

Define the kinetic energy store.

A

The amount of energy an object has as a result of its mass and speed.

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27
Q

What is the word equation for Kinetic energy?

A

Kinetic energy(Joules) = ½ x Mass(kg) x Velocity(m/s)

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28
Q

What is the mathematical equation for Kinetic energy?

A

Ek = ½ × m × v^2

where

Ek is in Joules

m is in kilograms

v is in Metres per second

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29
Q

Define the Gravitational potential energy store(GPE):

A

The energy an object has doe to its height in a gravitational field.

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30
Q

What is the word equation for GPE?

A

Gravitational Potential Energy = Mass x Gravitational Field Strength x Height

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31
Q

What is the mathematical equation for GPE?

A

Ep = m x g x h

where

m is in kilograms

g is in Newtons per kilogram (N/Kg)

h is in Metres

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32
Q

Define the Elastic Potential Energy store

A

The energy stored in an object when work is being done on the object.

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33
Q

What is the word equation for Elastic Potential Energy?

A

Elastic potential energy = 1/2 x Spring Constant x Square of Extension

34
Q

What is the Mathematical equation for Elastic Potential Energy?

A

Ee = 1/2 x k x e^2

35
Q

Describe the energy changes when a spring is stretched by a weight?

A

At the beginning:
- The spring has some energy in its elastic potential energy store because the spring is slightly compressed.
-The spring has NO energy in its kinetic energy store as it is stationary.
-The GPE of the spring is at a maximum because the mass is at it’s highest point.

As it is being stretched:
-The spring has some energy in its Elastic potential store because the spring is slightly stretched.
-The kinetic energy of the spring is at a maximum because

36
Q

Define Gravitational field strength:

A

The force of weight in Newtons for each kilogram of mass.

37
Q

What is specific heat capacity?

A

The amount of energy required to raise 1 kilogram of a substance by one degree.

38
Q

What is the mathematical equation for heat energy?

A

ΔE = mcΔθ

39
Q

What is the word equation for heat energy?

A

Change in energy = mass x specific heat capacity x change in temperature.

40
Q

What is the difference between an object with a high specific heat capacity and an object an with a low specific heat capacity.

A

Lower Specific heat capacity warms up and cools down quickly as it takes much less energy to change its temperature.

Higher specific heat capacity - warms up and cools down slowly as it takes far more energy to change its temperature.

41
Q

what is work done by forces?

A

Mechanical work is when a force acts over a distance.

Energy is transferred from the kinetic store of the person to the kinetic store of the box.

42
Q

What is power?

A

Energy transferred per unit time.

43
Q

What is the mathematical equation for power?

A

P = E / t

OR

P = W / t

44
Q

What is the word equation for power?

A

Power(Watts) = Energy transferred(J) / Time(s)

45
Q

Compare two motors, lifting two, equal masses. Motor A takes a short time, whereas Motor B takes a longer time.

A

-Motor A lifts the same weight W, to the same height H, but does it faster.

-The same work is done, in a shorter time. Therefore, Motor A has greater power.

46
Q

What is the mathematical equation for work done?

A

W = F x D

47
Q

What is the word equation for work done?

A

Work done = Force x Distance

48
Q

State the law of conservation of energy.

A

Energy cannot be created nor destroyed. It can only be transferred from one store to another.

49
Q

Energy in a closed system remains:

A

Constant

50
Q

Energy may be dissipated to:

A

The thermal store of its surroundings.

(In a closed system)

51
Q

Describe the energy changes, and dissipation, of a bat hitting a ball.

A

-The moving bat has energy in its Kinetic store

-Some of that energy is transferred usefully to the kinetic energy of the ball.

-Some of the energy is dissipated by heating to the thermal store of the bat.

52
Q

Describe the energy changes, and dissipation, of an electric heater.

A

-Energy is transferred electrically from the mains supply to the thermal store of the heating element.

-Some of that energy is usefully transferred to the thermal store of the surroundings by heating the air particles in the room.

-Some of the energy is dissipated to the thermal store of the surroundings.

53
Q

In practice, most systems tend to be:

A

Open Systems

54
Q

What types of energy does wasted energy tend to be?

A

Thermal.

Sound.

Light.

55
Q

Define Useful Energy:

A

The energy that is transferred from store to store and used for an intended purpose.

56
Q

Define Wasted (dissipated) Energy?

A

The energy that is not useful for the intended purpose and is dissipated to the surroundings.

57
Q

In what ways can loss/waste of energy be minimized?

A

Lubrication:

-Reduces friction in processes, which causes the dissipation of thermal energy

Insulation:
-Prevents thermal energy from being dissipated to the surroundings.

-Dependent on Insulation material used.

58
Q

What is Thermal Conduction?

A

-Thermal Conduction is the process where energy is transferred by vibrating particles in a substance.

59
Q

How does thermal conductivity effect the rate of energy transfer?

A

The higher the thermal conductivity of a material, the higher the rate of energy transfer by conduction across the material.

60
Q

What is an insulator?

A

An insulator is a material that is a poor conductor,

61
Q

What factors affect the rate of energy transfer across a material?

A

-Temperature difference;
Greater Temperature difference increases the rate of conduction

-Thickness of the material
Thicker materials have a lower rate of conduction.

-Thermal Conductivity
The Greater the thermal conductivity, the greater the rate of conduction.

62
Q

Define Efficiency:

A

The ratio of the useful energy output from a system to its total energy input.

63
Q

What is the equation for efficiency?

A

Efficiency = Useful power output / Total Power input.

64
Q

How can friction Be reduced?

A

-By lubrication

-Lubrication reduces friction, decreasing energy loss to thermal store of surroundings, and sound store of 1

65
Q

How can electrical resistance be reduced?

A

-Using components with low resistance

-Reducing the current

66
Q

How can air resistance be reduced?

A

-Streamlining the shaped of moving objects

67
Q

How can sound be reduced?

A

-Tightening lose parts to reduce vibration.

-Lubricating parts

68
Q

What are energy resources?

A

Large stores of energy that can be used to generate electricity and heat homes and businesses.

69
Q

What are fossil fuels?

A

Fossil fuels are combusted to heat water to produce steam to turn turbines and generate electricity.

70
Q

What is nuclear energy?

A

Nuclear fuels are reacted to heat water to produce steam to turn turbines to generate electricity.

71
Q

What are bio-fuels?

A

Plant-Matter, ethanol or methane can be produced and used as a fuel in place of fossil fuels

72
Q

What is wind energy?

A

Wind turbines turn directly to produce elctricity.

73
Q

What is Hydroelectricity?

A

Water is stored at a height, and when released, rushing water turns turbines.

74
Q

What is tidal energy?

A

The movement of water due to tides, turn turbines directly to generate electricity.

75
Q

What is geothermal electricity?

A

Hot rocks underground are used to heat water to produce steam to turn turbines which generate electricity.

76
Q

What is solar energy?

A

Solar cells use light to generate electricity, solar panels use thermal radiation to heat water to produce warm water for household use.

77
Q

What is water waves energy?

A

Moving water due to waves turn turbines directly to generate electricity.

78
Q

What is a renewable energy source?

A

An energy source that is replenished at a faster rate than the rate at which it is being used.

79
Q

What is the greenhouse effect?

A

-Global Warming is a problem caused by the greenhouse effect

-The greenhouse effect is Caused by the increased concentration and effect of greenhouse gasses

80
Q

What are the effects of Global warming?

A

-Climate Change due to increase in Earth’s temperature

-Sea levels will rise due to glaciers melting

-Mass Extinction due to destruction of natural habitats

-Migration of species to more habitable areas

-Spread of disease Caused by a warmer climate.

-Loss of habitat due to climate change

AQA GCSE Physics Higher (Triple) (3 decks)

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