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8Ne Year 7 Science > 7H Energy > Flashcards

7H Energy Flashcards

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1
Q

What is the conservation of energy?

A

Energy cannot be created or destroyed, only transferred from one store to another

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2
Q

What energy store fills up when a spring is stretched?

A

Elastic potential

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3
Q

What energy store empties as a skydiver falls?

A

Gravitational potential

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4
Q

State the four ways energy can be transferred.

A

Heating, mechanical, radiation, electrically

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5
Q

True or false? “Heat moves from cold places to hot places.”

A

False – heat energy is transferred from hot places to cold

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6
Q

How is all energy eventually stored?

A

Thermal

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7
Q

What is meant by “wasted energy”?

A

Energy which spreads out and transferred to less useful stores

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8
Q

What does the term dissipate mean?

A

Spread out

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9
Q

In what store is most dissipated energy?

A

Thermal

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10
Q

What is shown in a Sankey diagram?

A

Useful and non-useful energy transfers

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11
Q

What units are used to measure energy?

A

Joules, J

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12
Q

What does the thickness of the arrows in a Sankey diagram show?

A

The amount of energy transferred

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13
Q

Define efficiency.

A

How much of the energy transferred to a system is transferred usefully

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14
Q

How do you calculate efficiency?

A

(Useful output ÷ Total input) x 100

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15
Q

If a light bulb is described as 60% efficient, what does this mean?

A

It transfers 60% of the total energy input as useful energy (light)

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16
Q

What is a multicellular organism?

A

Organism with more than one cell

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17
Q

What is a tissue?

A

Collection of cells which work together to perform a function

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18
Q

Name a human organ system.

A

Digestive, circulatory, nervous

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19
Q

How does size of an organism affect its SA: V ratio?

A

Bigger the organism the smaller its SA: V ratio

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20
Q

How is surface area of a cube calculated?

A

Length x width x 6 (number of sides)

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21
Q

How is volume of a cube calculated?

A

Length x width x height

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22
Q

Give 2 adaptations of exchange surfaces.

A

Good blood supply, thin membrane, large surface area

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23
Q

Give two examples of exchange surfaces in humans.

A

Alveoli and villi

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24
Q

Name 4 fuels we may use at home.

A

Coal, wood, oil and natural gas

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25
Q

What do fuels react with during burning?

A

Oxygen

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26
Q

What unit of measurement is used for the energy found in foods?

A

Kilojoules or calories

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27
Q

How much energy will 2400 calories provide your cells with?

A

10 kJ

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28
Q

What happens if you consume too many calories?

A

Stored as chemical energy in fat cells

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29
Q

What energy store is in food and fuel?

A

Chemical

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30
Q

What are carbohydrates broken down into during digestion?

A

Glucose

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31
Q

Name 3 processes your body uses energy for.

A

Grow, move, reproduce, keep us warm, repair

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32
Q

What store of energy does a moving object have?

A

Kinetic energy

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33
Q

What do fuels react with when they are burned?

A

Oxygen

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34
Q

What type of organism eats both plants and other animals?

A

Omnivore

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35
Q

True or False: “The stamen is the male part of the plant”

A

TRUE

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36
Q

What colour will universal indicator turn in a strong acid?

A

Red

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37
Q

What is a neutralisation reaction?

A

An acid reacts with a base (or alkali)

38
Q

What is power?

A

The rate energy is transferred or work is done over time

39
Q

Describe what a power rating of 350 W means in words.

A

350 joules of energy is transferred per second

40
Q

How do we convert from W into kW?

A

Divide by 1000

41
Q

How many W are there in 3 kW?

A

3 x 1000 = 3000 W

42
Q

True or false? “Power can also be given the units Joules per second (J/s).”

A

TRUE

43
Q

State the equation that links energy transferred, power, and time.

A

Power = Energy transferred ÷ Time

44
Q

What unit of time do we use when calculating power?

A

Seconds

45
Q

In the picture on page 10, which appliance will transfer the most energy in 10 mins?

A

Cooker/oven

46
Q

What 2 charges does an energy bill contain?

A

Standing charge, the cost of energy per unit

47
Q

What unit of measurement do energy suppliers use?

A

Kilowatt-hours (kWh)

48
Q

How many joules are in 1 kWh?

A

3,600,000 Joules

49
Q

How many J of energy is transferred in 0.5 kWh?

A

1,800,000 Joules

50
Q

How is the equation for calculating energy similar to the equation for power?

A

Both have same variables – energy transferred, power, time

51
Q

How is the equation for calculating energy different to the equation for power?

A

Use different units of measurement – kWh, kW, hours

52
Q

What is the equation for calculating cost of energy?

A

Cost (p) = Energy transferred (kWh) x Cost per kWh of energy (p)

53
Q

Define renewable.

A

Can be replenished or replaced

54
Q

Name two examples of renewable energy resources.

A

Wind, waves, tides, sunlight, geothermal

55
Q

What energy store causes wind turbines to turn?

A

Kinetic

56
Q

Other than being renewable, state one benefit of wind turbines.

A

No fuel costs and no harmful polluting gases are produced

57
Q

Which renewable resource transfers energy from a gravitational energy store?

A

Hydroelectric

58
Q

How are waves used to generate electricity?

A

Kinetic energy of waves turns turbine

59
Q

State one negative impact tidal barrages have on the environment.

A

Destroy the habitats of estuary species, including wading birds

60
Q

How does hydroelectric power contribute to global warming?

A

Rotting vegetation underwater releases methane, which is a greenhouse gas

61
Q

What is geothermal energy?

A

Heat from underneath the Earth’s surface

62
Q

Give two ways of harnessing geothermal energy.

A

Using hot water and steam from deep underground or using hot rocks to heat up cold water

63
Q

Why can’t we use geothermal power in the UK?

A

Can only be used in certain areas

64
Q

State the energy transfer that occurs in a solar cell.

A

Light 🡪 electrical

65
Q

Why are solar cells also called photovoltaic cells?

A

Photo means light, volt is the measurement of electrical energy

66
Q

What is the difference between a solar cell and a solar panel?

A

Solar panels use thermal energy, solar cells use light

67
Q

How does a solar panel reduce our dependence on gas central heating?

A

Do not have to burn gas to heat up water in a boiler

68
Q

Why can solar power sometimes be an unreliable energy resource?

A

Does not work at night or when cloudy

69
Q

Define non-renewable.

A

Cannot be replenished and will run out

70
Q

Give 3 examples of fossil fuels.

A

Coal, oil and natural gas

71
Q

How are fossil fuels formed?

A

Dead plants and animals are buried over millions of years

72
Q

What energy store is found in fossil fuels?

A

Chemical

73
Q

How can we use the energy store in fossil fuels to generate electricity?

A

We burn them to release thermal energy, which heats up water into steam and this turns turbines

74
Q

Apart from being non-renewable, what is the major drawback of fossil fuels?

A

They contribute to global warming

75
Q

Why might people not want to live near a nuclear power station?

A

There is a risk of a nuclear melt down

76
Q

Give an example of the fuel used in a nuclear power station.

A

Uranium

77
Q

What does GPE stand for?

A

Gravitational potential energy

78
Q

What does GPE mean?

A

An energy store of objects that are raised within a gravitational field (meaning that they can fall)

79
Q

What is kinetic energy?

A

Energy stores of moving objects

80
Q

What unit is energy measured in?

A

Joules

81
Q

State the equation that links GFS, GPE, height and mass.

A

GPE = GFS x Height x Mass

82
Q

State the equation that links kinetic energy, mass and speed.

A

Kinetic energy = 0.5 x Mass x Speed²

83
Q

What is the GFS on Earth?

A

10 N/kg

84
Q

What is an elastic material?

A

A material that can be stretched or compressed

85
Q

How is elastic deformation different to inelastic deformation?

A

During elastic deformation, the material returns to its original shape. During inelastic deformation, it does not

86
Q

What does EPE stand for?

A

Elastic potential energy

87
Q

What is EPE?

A

An energy store of all elastic materials

88
Q

State the energy transfer when a compressed spring is released.

A

Elastic -> Kinetic

89
Q

What does the spring constant of a material tell us?

A

How stretchy an object or material is

90
Q

State the units for spring constant.

A

Newtons per metre (N/m)

91
Q

State the equation for calculating EPE.

A

0.5 x spring constant x extension²

8Ne Year 7 Science (11 decks)

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