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Science Flashcards

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

State the four ways energy can be transferred.

A

Heating, mechanical, radiation, electrically

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3
Q

How is all energy eventually stored?

A

Thermal

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4
Q

What is meant by “wasted energy”?

A

Energy which spreads out and transferred to less useful stores

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5
Q

What does the term dissipate mean?

A

Spread out

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6
Q

What is shown in a Sankey diagram?

A

Useful and non-useful energy transfers

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7
Q

What units are used to measure energy?

A

Joules, J

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8
Q

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

A

The amount of energy transferred

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9
Q

Define efficiency.

A

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

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10
Q

How do you calculate efficiency?

A

(Useful output ÷ Total input) x 100

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11
Q

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

A

Kilojoules or calories

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12
Q

How much energy will 2400 calories provide your cells with?

A

10 kJ

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13
Q

What happens if you consume too many calories?

A

Stored as chemical energy in fat cells

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14
Q

What energy store is in food and fuel?

A

Chemical

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15
Q

What are carbohydrates broken down into during digestion?

A

Glucose

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16
Q

Name 3 processes your body uses energy for.

A

Grow, move, reproduce, keep us warm, repair

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17
Q

What store of energy does a moving object have?

A

Kinetic energy

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18
Q

What do fuels react with when they are burned?

A

Oxygen

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19
Q

What is power?

A

The rate energy is transferred or work is done over time

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20
Q

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

A

350 joules of energy is transferred per second

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21
Q

How do we convert from W into kW?

A

Divide by 1000

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22
Q

How many W are there in 3 kW?

A

3 x 1000 = 3000 W

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23
Q

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

A

True

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24
Q

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

A

Power = Energy transferred ÷ Time

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25
Q

What unit of time do we use when calculating power?

A

Seconds

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26
Q

What 2 charges does an energy bill contain?

A

Standing charge, the cost of energy per unit

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27
Q

What unit of measurement do energy suppliers use?

A

Kilowatt-hours (kWh)

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28
Q

How many joules are in 1 kWh?

A

3,600,000 Joules

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29
Q

How many J of energy is transferred in 0.5 kWh?

A

1,800,000 Joules

30
Q

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

A

Both have same variables – energy transferred, power, time

31
Q

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

A

Use different units of measurement – kWh, kW, hours

32
Q

What is the equation for calculating cost of energy?

A

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

33
Q

Define renewable.

A

Can be replenished or replaced

34
Q

Name two examples of renewable energy resources.

A

Wind, waves, tides, sunlight, geothermal

35
Q

What energy store causes wind turbines to turn?

A

Kinetic

36
Q

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

A

No fuel costs and no harmful polluting gases are produced

37
Q

Which renewable resource transfers energy from a gravitational energy store?

A

Hydroelectric

38
Q

How are waves used to generate electricity?

A

Kinetic energy of waves turns turbine

39
Q

State one negative impact tidal barrages have on the environment.

A

Destroy the habitats of estuary species, including wading birds

40
Q

How does hydroelectric power contribute to global warming?

A

Rotting vegetation underwater releases methane, which is a greenhouse gas

41
Q

What is geothermal energy?

A

Heat from underneath the Earth’s surface

42
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

43
Q

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

A

Can only be used in certain areas

44
Q

State the energy transfer that occurs in a solar cell.

A

Light 🡪 electrical

45
Q

Why are solar cells also called photovoltaic cells?

A

Photo means light, volt is the measurement of electrical energy

46
Q

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

A

Solar panels use thermal energy, solar cells use light

47
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

48
Q

Why can solar power sometimes be an unreliable energy resource?

A

Does not work at night or when cloudy

49
Q

Define non-renewable.

A

Cannot be replenished and will run out

50
Q

Give 3 examples of fossil fuels.

A

Coal, oil and natural gas

51
Q

How are fossil fuels formed?

A

Dead plants and animals are buried over millions of years

52
Q

What energy store is found in fossil fuels?

A

Chemical

53
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

54
Q

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

A

They contribute to global warming

55
Q

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

A

There is a risk of a nuclear melt down

56
Q

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

A

Uranium

57
Q

What does GPE stand for?

A

Gravitational potential energy

58
Q

What does GPE mean?

A

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

59
Q

What is kinetic energy?

A

Energy stores of moving objects

60
Q

What unit is energy measured in?

A

Joules

61
Q

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

A

GPE = GFS x Height x Mass

62
Q

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

A

Kinetic energy = 0.5 x Mass x Speed²

63
Q

What is the GFS on Earth?

A

10 N/kg

64
Q

What is an elastic material?

A

A material that can be stretched or compressed

65
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

66
Q

What does EPE stand for?

A

Elastic potential energy

67
Q

What is EPE?

A

An energy store of all elastic materials

68
Q

State the energy transfer when a compressed spring is released.

A

Elastic -> Kinetic

69
Q

What does the spring constant of a material tell us?

A

How stretchy an object or material is

70
Q

State the units for spring constant.

A

Newtons per metre (N/m)

71
Q

State the equation for calculating EPE.

A

0.5 x spring constant x extension²

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