# Physics Topic 1 - Energy

What are the 8 energy stores?
Thermal, Kinetic, GPE, Elastic Potential, Chemical, Magnetic, Electrostatic and Nuclear
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What is a closed system?
A system where neither matter nor energy can enter or leave- the net change is always zero.
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What is work done and when does it happen?
Work done is energy transferred, and work can be done when current flows or by a force moving an object
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What kind of objects have kinetic energy and how does their amount of kinetic energy change?
Anything that is moving has kinetic energy; energy is transferred to this store when it speeds up and away from this store when it slows down
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Give the formula for kinetic energy
Kinetic energy (J) = 1/2 x mass (kg) x velocity^2 (m/s/s)
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How do objects gain gravitational potential energy?
Lifting an object in a gravitational field requires work. causing energy to be transferred to the gravitational potential store. The higher the object is lifted, the more energy transferred
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Give the formula for gravitational potential energy
Gravitational potential energy (J) = mass (kg) x gravitational field strength x height
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For a falling object when there's no air resistance...
Energy lost from the GPE store = energy gained in the kinetic energy store
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How is energy transferred to the elastic potential energy store?
By stretching or squashing an object
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Give the formula for elastic potential energy
Elastic potential energy (J) = 1/2 x Spring constant (N/m) x extension^2 (m)
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What is the definition of specific heat capacity?
Specific heat capacity is the amount of energy needed to raise the temperature of 1kg of a substance by 1 degree
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Give the formula that links energy transferred to specific heat capacity
Change in thermal energy (J) = mass (kg) x specific heat capacity (J/kg/degree) x temperature change (degrees)
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What is the definition of power?
The rate of energy transfer/the rate of doing work.
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What is the equation for power?
Power (W) = Work done (J) / Time (s) (one watt= one joule of energy transferred per second)
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What is conduction?
The process where vibrating particles transfer energy to neighbourhood particles. It usually occurs in a solid.
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What is convection?
This is where energetic particles move away from hot to cold. It can happen in gases and liquids.
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How can friction and air resistance be reduced?
Lubricants and streamlining.
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How can houses be insulated to prevent heat loss?
-have thick walls with low conductivity -cavity wall insulation (air or foam in the gap between two walls) -loft insulation (reduce convection currents) -double glazed windows -draught excluders
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What is the equation for efficiency?
Efficiency = useful output energy transfer/total input energy transfer OR useful power output/total power output
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Non-Renewable Energy Resources
They will run out one day and they do damage to the environment but they provide most of our energy. They include fossil fuels such as coal, oil and natural gas and nuclear fuel- uranium and plutonium.
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Renewable Energy Resources
They will never run out as the energy can be renewed as it is used. Most of them do damage the environment but not as much. They don't produce much energy and they are unreliable. They include: the sun, hydro-electricity, wind, bio-fuel, geothermal
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What can energy resources be used for?
Transport and heating.
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How is energy generated from wind?
Lots of wind turbines are put up in exposed places such as moors or coasts. They have generators inside them- the rotating blades turn and produce electricity.
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What are the advantages of wind turbines?
They do not give out pollution, there is no permanent damage to the landscape and there are no fuel costs and minimal running costs.
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What are the disadvantages of wind turbines?
They spoil the view, need 1500 wind turbines to replace 1 coal-fired power station, noise pollution, impossible to increase supply with extra demand, may stop when the wind stops or is too strong (70-85%), initial costs are high
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How is energy generated from solar power?
Solar cells generate electric currents directly from sunlight- they are useful for calculators and watched that don't use much electricity. It is often used in remote places and to power electric road signs and satellites.
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What are the advantages of solar power?
There's no pollution, it is very reliable in sunny countries, can still be cost effective in Britain, the energy is free and running costs are almost nil.
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What are the disadvantages of solar power?
They only work in the daytime, you can't increase the power output when there is extra demand, they use quite a lot of energy to manufacture and the initial costs are high.
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How is energy generated from geothermal power?
This is possible in volcanic areas or where hot rocks lie quite near to the surface. The source of much of the energy is the slow decay of various radioactive elements, including uranium, deep inside the earth.
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What are the advantages of geothermal power?
It is brilliant free energy that is reliable and does little damage to the environment, it can be used to generate electricity or heat buildings directly.
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What are the disadvantages of geothermal power?
There aren't very many suitable locations for power plants, and the cost of building one is often high compared to the amount of energy it produces.
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How is energy generated from hydro-electric power?
This usually requires the flooding of a valley by building a big dam, and water is allowed out through turbines.
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What are the advantages of hydro-electric power?
There is no pollution and it can provide an immediate response to an increased demand, mostly reliable except for in times of drought, there are no fuel costs and minimal running costs and it can be a useful way to generate electricity small scale.
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What are the disadvantages of hydro-electric power?
The flooding of the valley causes rotting vegetation which releases methane and carbon dioxide, possible loss of habitat/whole villages for some species, reservoirs can look unsightly when they dry up.
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How is energy generated from wave power?
This requires lots of small wave-powered turbines located around the coast, and the moving turbines are connected to a generator.
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What are the advantages of wave power?
There is no pollution and there are no fuel costs and minimal running costs. It can be very useful on small islands.
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What are the disadvantages of wave power?
They disturb the seabed and the habitats of marine animals, they spoil the view and are a hazard to boats.They are fairly unreliable as waves tend to die out when the wind drops
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How is energy generated from tidal barrages?
Tidal barrages are big dams built across river estuaries, with turbines in them. As the tide comes in it fills up the estuary and the water is then allowed out through turbines at a controlled speed. Tides are produced by the gravitational pull.
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What are the advantages of tidal barrages?
There is no pollution, and they are reliable as tides happen twice a day without fail. There are no fuel costs and minimal running costs and they have the potential for generating a significant amount of energy.
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What are the disadvantages of tidal barrages?
They prevent free access by boats, spoil the view and alter the habitat of wildlife. The height of the tide is variable so lower tides will provide less energy than spring tides, and they don't work when the water level is the same either side.
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What are bio-fuels?
They are renewable energy sources created from either plant products or animal dung. They can be solid, liquid or gas and can be burnt to produce electricity or run cars, just like fossil fuels.
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What are the advantages of bio-fuels?
They are supposedly carbon neutral (have to grow plants at the rate you're burning them), they are fairly reliable as crops grow quickly, they can be continuously produced and stored.
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What are the disadvantages of bio-fuels?
They can't respond to immediate energy demands, the cost to refine them is very high and growing crops specifically for fuel may mean less space and water for food crops, forest is sometimes cleared (loss of habitat), decay and burning are harmful
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What are the advantages of fossil fuels and nuclear energy?
They are reliable and produce enough energy to meet current demand, the running costs aren't that expensive, it is cost effective, it can respond quickly to changes in demand as they are extracted from the earth quickly, fairly low extraction costs
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What are the disadvantages of fossil fuels and nuclear energy?
They are slowly running out and if no new resources are found, the fuel may run out. The set up costs of power plants can be quite high and they create many environmental problems.
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What kind of environmental problems can fossil fuels and nuclear energy cause?
They release CO2 which adds to the greenhouse effect and results in global warming, they release sulphur dioxide which causes acid rain, coal mining makes a mess of the landscape, oil spillages can cause serious environmental problems...
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Question continues
Nuclear waste is dangerous and difficult to dispose of, nuclear fuel is relatively cheap but the cost of the power plant is expensive, nuclear power carries the risk of a major catastrophe.
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## Other cards in this set

### Card 2

#### Front

What is a closed system?

#### Back

A system where neither matter nor energy can enter or leave- the net change is always zero.

### Card 3

#### Front

What is work done and when does it happen?

### Card 4

#### Front

What kind of objects have kinetic energy and how does their amount of kinetic energy change?

### Card 5

#### Front

Give the formula for kinetic energy