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Energy Flashcards

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1
Q

Conservation of energy:

A

Energy is never created or destroyed, only transferred between different forms and objects, stored or dissipated

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2
Q

What is gravitational potential energy affected by?

A

An objects position in a gravitational field

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3
Q

What is nuclear energy made from?

A

From breaking apart atoms

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4
Q

What are the ways of transferring energy stores?

A

Mechanically, electrically, heating, through radiation

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5
Q

What is kinetic energy?

A

The energy an object possesses due to its motion

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6
Q

What is internal energy?

A

The total energy stored by the particles making up a substance or system

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7
Q

What two types of energy stores make up internal energy?

A

Kinetic and potential

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8
Q

What is specific heat capacity?

A

The amount of energy required/released to raise/lower the temperature of 1kg of a substance by 1 degree

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9
Q

For solids, how is heat trasferred?

A

Conduction

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10
Q

For fluids, how is heat transferred?

A

Fluids are liquid and gas. Heat is transferred via convection

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11
Q

How is heat transferred through empty space?

A

Radiation

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12
Q

What is conduction?

A

Heat transfer when vibrating particles transfer energy to neighbouring particles

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13
Q

How does conduction work?

A

Particles are put near a source of heat, and this energy is transferred to the kinetic energy store of the particles. They vibrate faster, collide with neighbouring particles more and transfer the kinetic energy on. Heat becomes evenly spread out

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14
Q

Why do fluids have a low thermal conductivity?

A

Their particles are more spread out so do not collide with each other as frequently, so cannot pass on kinetic energy in this way very effectively

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15
Q

What is convection?

A

Transfer of thermal energy through movement of fluids caused by differences in temperature and density

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16
Q

How does convection work?

A

Particles aren’t fixed, so when heated, they all move around freely and faster. By the process of random diffusion, the particles move from warmer region to cooler region. Causes warmer region to have more spread out particles than cold. This means it technically expands and becomes less dense.

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17
Q

Why do convection currents occur?

A

When the particles heat up and expand, they become less dense. This means they rise above the cooler particles. The cooler particles sink down to take their place and process repeats

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18
Q

What do convection and conduction have in common?

A

Both involve particles gaining energy

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19
Q

How can heat energy travel through a vacuum?

A

Via infrared radiation. All objects constantly emit and absorb infrared radiation

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20
Q

How can you reduce energy loss in buildings?

A
  • doors closed with foam seals to reduce heat energy lost through convection in air
  • cavity walls with insulating foams to reduce convection and conduction
  • double/triple glazed windows to reduce conduction (air is poor conductor)
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21
Q

How can your reduce energy loss via friction on surfaces?

A

Use lubricant e.g. oil to reduce friction

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22
Q

What is friction?

A

The resistance that one object encounters when moving over a solid or through a fluid

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23
Q

How can you reduce energy loss from friction due to air resistance?

A

Streamlining

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24
Q

What is power?

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A

The rate at which energy is transferred, or at which work is done

25
What is work done?
Energy required when a force is used to move an object by a certain distance
26
Efficiency:
The proportion of useful energy output generated from energy supplied
27
What is a fossil fuel?
A hydrocarbon-containing material formed naturally in the earth's crust made from the remains of dead plants and animals
28
What are the 3 types of fossil fuel?
Coal, oil, natural gas
29
What are fossil fuels burnt to produce - and what is this used for?
Provide heat for direct use e.g. cooking, power engines (internal combustion), to generate electricity
30
What are the conditions required for fossil fuels to be made?
High pressure, high heat, millions of years
31
Pros of fossil fuels?
Relatively cheap, can be used in any conditions, current infrastructure is designed to run using fossil fuels
32
Cons of fossil fuels?
Limited resource so will run out, produce CO2 when burned so global warming, sometimes produce toxic gases when burned
33
How is nuclear energy obtained?
Via nuclear reactions such as nuclear fission in power stations
34
What can nuclear energy be used for?
Generate electricity and transmitted to homes and factories across the country
35
Pros of nuclear energy?
Do not produce any pollutants, can be used in any conditions, fuel is limited but unlikely to run out for a very long time
36
Cons of nuclear energy
Technically fuels are a finite resource, produce radioactive waste which remains harmful for a long time and must be stored carefully, expensive, chance of nuclear meltdown
37
How is wind energy obtained?
Wind turbines placed in exposed areas with strong winds
38
How do wind turbines work?
The kinetic energy of the turning turbine transferred to generator where it is converted into electrical energy
39
Where is solar power from?
Energy obtained directly from sunlight
40
What is solar power used for?
Watches, calculators, remote regions that aren't connected to mains power supply, larger scale can power entire towns
41
Pros of solar and wind energy?
Low running costs, don't damage the environment, are getting cheaper every year
42
Cons of solar and wind energy?
High upfront costs, making them produces pollutants, dependent on the weather so unreliable, no way to increase supply at peak demand, takes up lots of space
43
What is geothermal energy?
Thermal energy generated and stored in the earth's crust from radioactive decay
44
What can geothermal energy be used for?
Directly for heat, or to generate electricity
45
Describe using geothermal directly for heat
Cheaper than generating electricity. Involves pumping water into the ground so it heats up, then back up to heat homes
46
Describe using geothermal to generate electricity
Pump water into ground, leave until it turns into steam. As steam rises, it turns turbines which drives generators that transfer kinetic into electrical energy.
47
Cons of geothermal energy?
Can only use in certain areas like volcanic regions, power plants can be expensive to rebuild
48
Pros of geothermal energy
Installing only slightly damages environments, running it doesn't produce pollutants, renewable so is reliable over long periods
49
Why can geothermal only be used in specific areas
Rock must be hot enough and lie near enough to the surface to be accessible
50
What are biofuels?
Fuels made from recently living organisms
51
Why are biofuels generally made from plants or algae?
They photosynthesise so can lock up the sun's energy which can be released later when burned (Animal waste is also used at small scales)
52
Why are biofuels considered carbon-neutral?
Though they release CO2, it was taken up while they were growing, so there was no overall release of CO2
53
Pros of biofuels?
Renewable, cheap to make, easy to transport, can mix with fossil fuels so we don't have to get new cars
54
Cons of biofuels?
Space to grow plants might need to be deforested first, harvesting + processing + transport require lots of energy (All releases lots of Co2)
55
How do hydroelectric dams work?
Use dams to trap water from upstream, creating reservoirs
56
How do tidal barrages work?
Dams make use of tides (trap water from high tide so that when tide goes back out, one side of dam is left with much higher water level)
57
How do HE dams and tidal barrages use difference in water levels to produce electricity?
Stored water has huge amounts of GPE. When water is released, turbines spin, in turn spinning a generator which converts it to electrical energy. After, the water just flows back into the river
58
Pros of HE dams and tidal barrages?
- large amounts of energy - no pollution - reliable - low running costs - large and small scale uses - increased response to immediate demand
59
Pros of HE dams and tidal barrages?
Often flood huge areas Big impact on surrounding environment Can submerge habitats and even whole villages Initial setup is expensive

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