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Energy New Flashcards

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Physics 101 flashcards AP® Physics flashcards
1
Q

system

A

an object or group of objects

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2
Q

what happens when there is a change to a system

A

energy is transferred

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3
Q

when do objects have kinetic energy

A

moving energy have energy in their kinetic store

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4
Q

when do objects have gravitational energy gravitational energy

A

objects gain energy in their gravitational potential store when they are lifted through a gravitational field

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5
Q

Elastic

A

Objects have energy in their elastic potential store if they are stretched, squashed or bent

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6
Q

Magnetic

A

Magnetic materials interacting with each other have energy in their magnetic store

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7
Q

Electrostatic

A

Objects with charge (like electrons and protons) interacting with one another have energy in their electrostatic store

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8
Q

Chemical

A

Chemical reactions transfer energy into or away from a substance’s chemical store

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9
Q

Nuclear

A

Atomic nuclei release energy from their nuclear store during nuclear reactions

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10
Q

Thermal

A

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

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11
Q

Mechanical working

A

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

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12
Q

Electrical working

A

A charge moving through a potential difference (e.g. current)

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13
Q

Heating (by particles)

A

Energy is transferred from a hotter object to a colder one (e.g. conduction)

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14
Q

(Heating by) radiation

A

Energy transferred by electromagnetic waves (e.g. visible light)

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15
Q

principle of conservation of energy

A

energy cannot be created or destroyed, it can only be transferred from one store to another

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16
Q

what is the total energy transferred into a system equal to

A

total energy transferred out of they system

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17
Q

how can energy be transferred to the surroundings

A

dissipated to the surroundings by heating and radiation

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18
Q

efficiency

A

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

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19
Q

equation for efficiency

A

efficiency = (useful energy output)/(total energy output) x 100%

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20
Q

equation for total energy

A

total energy output = useful energy output + wasted energy

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21
Q

how to represent useful energy in a sankey diagram

A

straight arrow pointing to the right

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22
Q

how to represent wasted energy in a sankey diragram

A

arrows that bend away

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23
Q

how to represent total energy in a sankey diagram

A

left hand side of the arrow represents total energy transferred into the system

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24
Q

method of energy transfer is solids

A

conduction

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25
Q

conduction

A

transfer of heat energy through the vibration of particles causing adjacent particles to gain kinetic energy

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26
Q

what are insulators used for in heating

A

used to prevent energy transfer by conduction

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27
Q

what makes a material a good conductor

A

if t transfers energy by heating

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28
Q

why are materials containing small trapped air
better insulator

A

air is a poor conductor, it cannot move around so it must transfer energy by conduction

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29
Q

how does energy transfer in conduction

A

when a substance is heated, the atoms start to move around(vibrate) more. As they bump into each other, they transfer energy from atom to atom

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30
Q

why are metals good at conducting heat

A

delocalised electron can collide with the atoms, helping to transfer vibrations through the material and hence transfer better heat

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31
Q

main method thermal energy is transferred in liquids and gases

A

convection

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32
Q

convection

A

transfer of heat through fluids by the upwards movement of warmer, less dense fluids

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33
Q

convection currents

A

-fluid is heated
-molecules push each other apart, making the fluid expand
-makes the hot fluid less dense that the surroundings
-hot fluid rises, and the cooler fluid moves in to take its place
-eventually the hot fluid cools, contracts and sinks back down again

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34
Q

what do objects emit(related to thermal)

A

infrared radiation

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35
Q

how does the temperature of an object affect the infrared radiation it emits

A

the hotter the object. the more infrared radiation it radiates in a given time

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36
Q

qualities of a black object in terms of absorbing and emitting

A

good absorber and emitter

37
Q

qualities of a dark object in terms of absorbing and emitting

A

reasonable absorber and emitter

38
Q

qualities of a white object in terms of absorbing and emitting

A

poor absorber and emitter

39
Q

qualities of a shiny object in terms of absorbing and emitting

A

very poor absorber(reflects) and emitter

40
Q

experiment to investigate conduction

A
  1. Attach ball bearings to the ends of each metal strip at an equal distance from the centre, using a small amount of wax
  2. The strips should then be turned upside down and the centre heated gently using a bunsen burner so that each of the strips is heated at the central point where they meet
  3. When the heat is conducted along to the ball bearing, the wax will melt and the ball bearing will drop
  4. Time how long this takes for each of the strips and record in a table
  5. Repeat the experiment and calculate an average of each time
41
Q

experiment to investigate convection

A
  1. Fill the beaker with cold water (not too full) and place it on top of a tripod and heatproof mat
  2. Pick up the crystal (potassium permanganate) using forceps and drop it into the centre of the beaker – do this carefully to ensure the crystal does not dissolve prematurely
  3. Heat the beaker using the Bunsen burner and record observations
  4. Repeat experiment with hot water and record observations
    (temp of water and rate of convection indep and dep variable)
42
Q

why is convection current faster in hot water

A

the higher the temperature, the higher the kinetic energy of the water molecules

43
Q

experiment to investigate radiation

A
  1. Set up the four identical flasks painted in different colours: black, grey, white and silver
  2. Fill the flasks with hot water, ensuring the measurements start from the same initial temperature
  3. Note the starting temperature, then measure the temperatures at regular intervals, e.g. every 30 seconds for 10 minutes
44
Q

how to reduce wasted energy transfers by conduction

A

use materials with a low thermal conductivity(insulators)

45
Q

how to prevent wasted energy transfers by convection

A

fluid that forms the currents must be prevented from moving

46
Q

factors of the effectiveness of a insulator

A

-thermal conductivity of the material
-density - particles closer together, easily transfer energy to one another more easily
-thickness of the material

47
Q

how good of conductors are gases

A

bad

48
Q

Work done

A

Energy transferred

49
Q

work done units

A

joules OR newton metres

50
Q

What happens when a force acts in the direction that the object is moving

A

Object gains energy(kinetic)

51
Q

What happens when a force acts in the opposite direction to the movement of an object

A

The object will lose energy, dissipated

52
Q

work done equation

A

w = f x d

53
Q

gravitational energy definition

A

the energy an object has due to its height in a gravitational field

54
Q

GPE equation

A

GPE = mx g x h

55
Q

gravitational field strength on Earth

A

10N/kg

56
Q

kinetic energy definition

A

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

57
Q

kinetic energy equation

A

1/2 x m x v²

58
Q

power

A

work done per unit time

59
Q

equation for power and energy

A

P = W/t
W = work done

60
Q

unit for power

A

watts or joules per second

61
Q

renewable energy souce

A

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

62
Q

how is electricity generated

A

a turbine is turned, which turns a generator, which generates electricity

63
Q

how do fossil fuels generate electricity

A

they are combusted to heat water, and the steam produced can be used to turn turbines

64
Q

fossil fuel energy transfers

A

chemical - thermal - kinetic - kinetic - transferred away electricity

65
Q

fossil fuels

A

Fossil fuels are combusted to heat water to produce steam that turns turbines to generate electricity

66
Q

Nuclear

A

Nuclear fuels are reacted to heat water to produce steam that turns turbines to generate electricity

67
Q

Bio fuels

A

Crops are grown to produce ethanol or methane, which can be used in place of fossil fuels

68
Q

Wind

A

Wind is used to turn turbines to generate electricity

69
Q

Hydroelectric

A

Water is stored at a height, and when released the moving water is used to turn turbines to generate electricity

70
Q

Tidal

A

Water is stored at a height (by a tidal barrage) at high and low tide, when released the moving water is used to turn turbines to generate electricity

71
Q

Wave

A

The motion of the water due to waves is used to turn turbines to generate electricity

72
Q

Geothermal

A

Hot rocks underground are used to heat water to produce steam that turns turbines to generate electricity

73
Q

Solar cells

A

Solar cells use sunlight to generate electricity

74
Q

Solar panels

A

Solar panels use sunlight to heat water in the panel to produce warm water for households

75
Q

fossil fuels advantages

A

Reliable. Can produce large amounts of energy consistently. Can respond to changes in demand.

76
Q

fossil fuels disadvantages

A

Produces carbon dioxide (CO2) which contribute to global warming, and sulphur dioxide, which causes acid rain

77
Q

nuclear advantages

A

Reliable. Produces large amounts of energy consistently. Produces no pollution or CO2. Large amounts of energy are produced from small amounts of fuel.

78
Q

nuclear disadvantages

A

Produces radioactive waste that takes thousands of years to decay and must be safely disposed of. Nuclear power stations are expensive to build and maintain, and take many years to build. Can not be turned on and off quickly so cannot respond to changes in demand.

79
Q

Bio fuels advantages

A

The CO2 released from combustion is balanced by the CO2 absorbed in photosynthesis, so could be considered carbon neutral

80
Q

bio fuels disadvantages

A

Land and resources used to grow crops are needed to grow food crops

81
Q

wind advantages

A

Produces no pollution or CO2. Are cheap to build and maintain. can be offshore. only small number of turbines required

82
Q

wind disadvantages

A

Non-reliable. Only generate electricity when the wind is blowing in a certain direction. Some people consider them visual pollution (they spoil the view)

83
Q

tidal energy advantages

A

Tides are very predictable, so energy can be produced at regular intervals

84
Q

tidal energy disadvantages

A

Few suitable locations (estuaries). Can harm aquatic life and disrupt shipping

85
Q

geothermal energy advantages

A

Reliable
-does not take up a lot of land

86
Q

geothermal energy disadvantages

A

Not many suitable locations. Can release methane (a greenhouse gas) in the extraction process.

87
Q

solar energy advantages

A

Produces no pollution or greenhouse gases. Good for electricity production in remote areas. Can be put on existing buildings

88
Q

solar energy disadvantages

A

Non-reliable. Only generates electricity when the Sun is shining. Each solar cell only produces a small amount of electricity so many cells are needed.

89
Q

advantages of renewable energy

A

-no GHGs produced
-does not run out

Physics (14 decks)

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