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Science 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

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
What unit of time do we use when calculating power?
Seconds
26
What 2 charges does an energy bill contain?
Standing charge, the cost of energy per unit
27
What unit of measurement do energy suppliers use?
Kilowatt-hours (kWh)
28
How many joules are in 1 kWh?
3,600,000 Joules
29
How many J of energy is transferred in 0.5 kWh?
1,800,000 Joules
30
How is the equation for calculating energy similar to the equation for power?
Both have same variables – energy transferred, power, time
31
How is the equation for calculating energy different to the equation for power?
Use different units of measurement – kWh, kW, hours
32
What is the equation for calculating cost of energy?
Cost (p) = Energy transferred (kWh) x Cost per kWh of energy (p)
33
Define renewable.
Can be replenished or replaced
34
Name two examples of renewable energy resources.
Wind, waves, tides, sunlight, geothermal
35
What energy store causes wind turbines to turn?
Kinetic
36
Other than being renewable, state one benefit of wind turbines.
No fuel costs and no harmful polluting gases are produced
37
Which renewable resource transfers energy from a gravitational energy store?
Hydroelectric
38
How are waves used to generate electricity?
Kinetic energy of waves turns turbine
39
State one negative impact tidal barrages have on the environment.
Destroy the habitats of estuary species, including wading birds
40
How does hydroelectric power contribute to global warming?
Rotting vegetation underwater releases methane, which is a greenhouse gas
41
What is geothermal energy?
Heat from underneath the Earth’s surface
42
Give two ways of harnessing geothermal energy.
Using hot water and steam from deep underground or using hot rocks to heat up cold water
43
Why can’t we use geothermal power in the UK?
Can only be used in certain areas
44
State the energy transfer that occurs in a solar cell.
Light 🡪 electrical
45
Why are solar cells also called photovoltaic cells?
Photo means light, volt is the measurement of electrical energy
46
What is the difference between a solar cell and a solar panel?
Solar panels use thermal energy, solar cells use light
47
How does a solar panel reduce our dependence on gas central heating?
Do not have to burn gas to heat up water in a boiler
48
Why can solar power sometimes be an unreliable energy resource?
Does not work at night or when cloudy
49
Define non-renewable.
Cannot be replenished and will run out
50
Give 3 examples of fossil fuels.
Coal, oil and natural gas
51
How are fossil fuels formed?
Dead plants and animals are buried over millions of years
52
What energy store is found in fossil fuels?
Chemical
53
How can we use the energy store in fossil fuels to generate electricity?
We burn them to release thermal energy, which heats up water into steam and this turns turbines
54
Apart from being non-renewable, what is the major drawback of fossil fuels?
They contribute to global warming
55
Why might people not want to live near a nuclear power station?
There is a risk of a nuclear melt down
56
Give an example of the fuel used in a nuclear power station.
Uranium
57
What does GPE stand for?
Gravitational potential energy
58
What does GPE mean?
An energy store of objects that are raised within a gravitational field (meaning that they can fall)
59
What is kinetic energy?
Energy stores of moving objects
60
What unit is energy measured in?
Joules
61
State the equation that links GFS, GPE, height and mass.
GPE = GFS x Height x Mass
62
State the equation that links kinetic energy, mass and speed.
Kinetic energy = 0.5 x Mass x Speed²
63
What is the GFS on Earth?
10 N/kg
64
What is an elastic material?
A material that can be stretched or compressed
65
How is elastic deformation different to inelastic deformation?
During elastic deformation, the material returns to its original shape. During inelastic deformation, it does not
66
What does EPE stand for?
Elastic potential energy
67
What is EPE?
An energy store of all elastic materials
68
State the energy transfer when a compressed spring is released.
Elastic -> Kinetic
69
What does the spring constant of a material tell us?
How stretchy an object or material is
70
State the units for spring constant.
Newtons per metre (N/m)
71
State the equation for calculating EPE.
0.5 x spring constant x extension²

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