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Physics > Topic 1 - Energy > Flashcards

Topic 1 - Energy Flashcards

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1
Q

What are the 8 energy stores you need to know?

A 
Kinetic
Thermal
Gravitational potential
Electrostatic
Nuclear
Magnetic
Chemical
Elastic potential
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2
Q

What is a system?

A

A group of or a single object you are interested in.

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3
Q

Where can energy be transferred (not counting closed systems)?

A

Into the system, away from the system, into a different object in the system or into a different energy store in the system. This is known as a change in the system.

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4
Q

How is most energy transferred? Give an example of a system including this.

A

By heating. A kettle transfers electrical energy into thermal energy, which heats the water.

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5
Q

What is work done and how does it occur?

A

Work done is energy transfer. It is done by resistance in a current or when a force acts on something.

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6
Q

What is the formula for kinetic energy?

A

Ek = 1/2 mv squared

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7
Q

What is the formula for gravitational potential energy?

A

Ep = mgh

G means gravitational field strength

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8
Q

What is the formula for elastic potential energy?

A

Ee = 1/2ke squared

K means spring constant in N/m and e means extension in metres.

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9
Q

What is the definition of specific heat capacity?

A

The amount of energy needed to raise the temperature of 1kg of a substance by 1 degree celsius.

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10
Q

What is the formula for specific heat capacity?

A 
DeltaE = mcDELTAtheta
Delta is a triangle meaning 'change in'
E is thermal energy in J
m is mass in kg
c is s.h.c in J/kg degrees celsius
theta is a circle with a line in it meaning temperature change in degrees celsius.
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11
Q

What is the conservation of energy principle? How does it apply to gravitational potential energy?

A

Energy can never be created and destroyed, only transferred. Energy lost by g.p.e = energy gained in kinetic store.

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12
Q

What is dissipated energy known as and why?

A

‘Wasted energy’ because the energy has been transferred in a way that isn’t useful to us.

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13
Q

Define power. What are the two equations for power?

A

Power is the rate of doing work.
P = Et where E is energy in J and t is time in seconds.
P = W / t where W is work done in J

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14
Q

What is a ‘powerful machine’?

A

A machine that can transfer a lot of energy in a short space of time.

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15
Q

Define conduction.

A

Conduction is the process where vibrating particles transfer energy to neighboring particles.

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16
Q

Define convection. What two states does it occur in?

A

Convection is the movement of energetic particles from hotter to cooler regions. It occurs in liquids and gases.

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17
Q

How does a radiator create a convection current?

A

Energy is transferred from the radiator into the air by conduction. The warmer air is less dense, so it rises. As it cools, it becomes less dense and moves down. It then gets heated by the radiator again and the cycle continues.

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18
Q

How do you reduce frictional forces causing energy to dissipate?

A

Use a lubricant such as oil.

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19
Q

Name two insulating methods to avoid loss of energy by heating in a house.

A

Thick walls with a low thermal conductivity.
Thermal insulation, such as loft insulation to prevent convection and double glazed windows to stop heat loss through conduction through the windows.

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20
Q

What are the equations for efficiency?

A

Useful output energy transfer / total input energy transfer.

Useful power output / total power output.

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21
Q

What is the only device with 100% efficiency and why?

A

An electric heater because all of the energy is turned into useful stores.

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22
Q

What does all energy ultimately become?

A

Thermal energy.

23
Q

What are 3 non-renewable energy sources? What are their 3 features?

A

Coal, oil and natural gas.

They will run out one day. They do damage to the envirop=nment. They provide most of our energy.

24
Q

What are 7 renewable energy sources? What are their 3 features?

A

Geothermal, wind, tidal, solar, hydro-electric, bio-fuel and water waves.
They will never run out. They do less damage to the environment. They are less reliable and don’t produce as much energy.

25
Q

Name 2 things energy resources are used for.

A

Transport, such as petrol cars and coal steam trains and electric cars.
Heating, such as coal fireplaces and natural gas radiators and solar heaters.

26
Q

How do wind turbines generate electricity?

A

They are placed in exposed places and when the wind hits them they spin, turning a turbine that generates electricity.

27
Q

What are the advantages of wind turbines?

A

They do not produce pollution except for when they are manufactured.
There are very small running costs and no fuel costs.
No permanent damage to the landscape.

28
Q

What are the issues with wind turbines?

A

They spoil the view.
You need 1500 to match 1 coal power station.
They’re noisy.
They can’t increase output to meet demands.
They only output energy 70 - 85% of the time due to weather dependency.
High initial costs.

29
Q

Where are solar cells used?

A

In remote places and on road signs and satellites.

30
Q

What are the advantages of solar cells?

A

There’s no pollution.
They’re reliable when the sun is out, but can still be cost effective in countries like the UK.
The energy is free and there are few running costs.

31
Q

What are the issues of solar cells?

A

They use a lot of energy to manufacture.
You can’t meet demands.
The initial costs are high.
They’re often used on a relatively small scale.

32
Q

Where is geothermal power generated?

A

It is generated in volcanic areas or areas with decaying elements such as uranium underground.

33
Q

What are the advantages of geothermal energy?

A

It is free and there are no running costs.
It is very reliable.
It can generate electricity or heat homes directly.

34
Q

What are the issues with geothermal energy?

A

There aren’t many suitable locations for power plants.

Power plants are very expensive compared to the amount of energy produced.

35
Q

How is hydro-electric power generated?

A

A large dam is built, flooding a valley, and water is allowed out through turbines.

36
Q

What are the advantages of hydro-electric power?

A 
No pollution.
Immediate response to increased demand.
Reliable except in drought.
No fuel and minimal running costs.
Useful in smaller areas.
37
Q

What are the issues with hydro-electric power?

A

Loss of habitat.
Looks unsightly when the reservoir dries up.
High initial costs.

38
Q

How is wave power generated?

A

Lots of wave-powered turbines are placed around the coast and are connected to a generator.

39
Q

What are the advantages of wave power?

A

No pollution.
Minimal fuel and running costs.
Useful on small islands.

40
Q

What are the issues with wave power?

A

Disturb the seabed and habitats of marine animals.
Hazardous to boats.
Spoil the view.
Can’t generate electricity on a large scale.
Unreliable.
High initial costs.

41
Q

How is tidal power generated?

A

A tidal barrage is built across a river estuary. Tides produced by the pull of the Sun and Moon create tides which go inside the barrage and are released at a controlled speed, going through turbines.

42
Q

What are the advantages of tidal power?

A

No pollution.
Reliable.
No fuel or running costs.
Can generate a significant amount of energy.

43
Q

What are the issues with tidal power?

A 
Prevent boat access.
Spoil the view.
Affect wildlife.
Relies on the size of the tides, so small neap tides will not generate as much.
Moderately high initial costs.
44
Q

How are biofuels used to generate energy?

A

Biofuels are solid, liquid or gas and can include plants and animal dung. They are burnt and can provide energy for things like cars.

45
Q

What are the advantages of biofuels?

A

Reliable.

Supposedly carbon neutral.

46
Q

What are the issues with biofuels?

A

Carbon neutrality is being debated.
Can’t respond to immediate energy needs (there is storage for this)
Costs to refine are high.
Concerns over there being enough space to grow crops for food vs fuel.
Large areas of vegetation have been cleared, affecting the environment and damaging habitats due to release of CO2 and methane.

47
Q

Why are non-renewables reliable?

A

They can meet current demands.
They’re extracted at a fast enough rate.
It is cost effective - extraction and running costs are low.

48
Q

What are the issues with coal power?

A

Release of CO2 contributing to global warming.
Sulfur dioxide released causing acid rain.
Mining and power plants (especially open-cast) can spoil landscapes.

49
Q

What are the issues with oil power?

A

Release of CO2 contributing to global warming.
Sulfur dioxide released causing acid rain.
Oil spillages cause serious environmental issues.

50
Q

What are the issues with nuclear power?

A

It is clean but waste is harmful and tricky to dispose of.
Fuel is cheap but decommissioning and building plants is very expensive.
Nuclear accidents such as Chernobyl are a risk.

51
Q

How has UK energy consumption changed between the 20th century and today?

A

In the 20th century, we demanded more electricity. Now, we are better at making efficient devices and so the demand for electricity is decreasing.

52
Q

What are the UK’s goals for use of renewable energy?

A

We aim to have 15% of energy generated by renewables by 2020.

53
Q

Why do more people want to use renewable energy?

A

People are getting more concerned about the lack of non-renewables in the future and the damage they do.
Pressure from other countries, us and the government creates targets for energy companies and leaders to create plans to reduce our non-renewable energy consumption.
Popularity for products such as electric cars are increasing.

54
Q

What 3 things is the use of renewables limited by and why?

A

1) Reliability - we will have to increase power plants, which is expensive, or research how to improve reliability.
2) Money - they’re more expensive to build, and some people can’t afford the higher costs. Research on reliability is also expensive.
3) Politics- some people argue they are unethical. Personal changes are expensive. There are protests around living near power plants and about the costs that will need to be made.

Physics (10 decks)

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