Energy Transfers Flashcards
Kinetic energy
Anything moving has energy in its kinetic energy store
Thermal energy
Any object - the hotter it is, the more energy it has in its store
Chemical
Anything that can release energy by a chemical reaction
Eg: foods, fuels
Gravitational potential
Anything in a gravitational field
Elastic potential
Anything stretched like springs and rubber bands
Electrostatic
Eg: two charges that attract or repel each other
Magnetic
Eg: two magnets that attract or repel each other
Nuclear
Atomic nuclei release energy from this store in nuclear reactions
Mechanically transferred
An object moving due to a force acting on it
Eg: pushing, pulling, stretching or squashing
Electrically transferred
A charge moving through a potential difference
Eg: charges moving round a circuit
By heating
Energy transferred from a hotter object to a colder object
Eg: heating a pan of water on a hob
By radiation
Energy transferred
Eg: by light/sound waves
Eg: energy from the sun reaching earth as light
What is the principle of conservation of energy?
Energy can be stored, transferred between stores, and dissipated - but it can never be created or destroyed
The total energy of a closed system has no net change
What is the equation used to calculate efficiency?
Efficiency = useful energy output / total energy output x 100%
Describe energy transfers of a ball rolling up a slope
1) Transferred MECHANICALLY from the KINETIC energy store of the ball to its GRAV POT energy store.
2) some energy transferred MECHANICALLY to its THERMAL energy stores of ball and the slope due to friction, then by heating to THERMAL energy stores of surroundings - energy is wasted
Describe energy transfers a bat hitting a ball
1) some energy is usefully transferred MECHANICALLY from the kinetic energy store of bat to kinetic energy store of ball.
2) Rest of energy is wasted. Some energy in kinetic energy store of bat is transferred MECHANICALLY to the thermal energy stores of bat, ball and surroundings.
3) remaining energy carried away by sound.
Describe energy transfers of an electric kettle boiling water
1) energy transferred electrically from mains to the thermal energy store of kettles heating element.
2) it is then transferred by heating to thermal energy store of water.
3) some energy is wasted and transferred by heating from thermal energy stores of heating element and water to the thermal energy stores of surroundings.
Battery powered toy cars
1) energy usefully transferred electrically from the chemical energy store of batter to kinetic energy store of car and carried away by light from headlights.
2) wasteful energy transfers occur, to thermal energy stores of car and surroundings and waste fully carried away by sound
Energy transfers in fossil fuels
1) As the fossil fuel burn, it transfers energy by heating and stored in the thermal energy store of water and steam.
2) Then, the energy is transferred mechanically to the turbine.
3) The energy is transferred mechanically to the generator, and then transferred as electricity.
Advantages of fossil fuels
1) readily available and provide reliable source of power
2) gas fired power stations can be turned on and off at short notice, thereby allowing electricity companies to respond to changes in demand throughout the day
Disadvantages to fossil fuels
1) non-renewable and produce gases which contribute to global warming and cause pollution.
2) we have limited reserves of all the fossil fuels
Energy transfers in nuclear power
During the process, energy is transferred from nuclear energy stores to thermal energy stores by heating, then mechanically to kinetic energy stores, and finally transferred electrically through the national grid
Advantages of nuclear power
1) plenty of nuclear fuel so resources will last for a long time
2) great amount of energy released for each kg of nuclear fuel
3) does not produce gases which contribute to global warming
Disadvantages of nuclear power
1) produce radioactive waste which has a long half-life
2) waste needs to be stored safely for many years
3) expensive to produce
Energy transfers in wind power
Wind turbines use energy from the kinetic energy store of moving air to generate electricity.
Wind turns blades, which turn a generator inside it.
Advantages of wind power
Wind power is clean and has no waste products
Renewable
Disadvantages of wind power
Unreliable - if wind is too light no power is generated
If wind too strong turbines can overheat
Make a noise that disturbs people living close to them
Energy transfers in tidal barrages
The energy is transferred from the kinetic energy stores of the water to the kinetic energy store of the turbine, and used to generate electricity.
Advantages of water power
Reliable and have no waste products
Hydroelectric power is reliable because rivers usually flow
Water is free and does not need mining or transporting
Disadvantages of water power
- initial costs are high
- environmental issues
Energy transfers in geothermal power
Water is pumped in pipes down to hot rocks and forced back up due to pressure to turn a turbine which drives a generator.
So the energy is transferred from thermal energy stores to kinetic energy stores and are used to generate electricity
Advantages of geothermal power
Renewable and reliable
Cheap
No waste products
Disadvantages of geothermal power
Only available in some regions of geological activity like Iceland.
Energy transfers in solar heating systems
Radiation from sun transfers to the thermal energy store of water.
Water is pumped through pipes, which are placed on the roof of a house. In this way the water is warmed.
Advantages of solar power
Once panels are installed solar power is free at source
Require little maintenance
Good long term investment
Renewable
No waste products
Disadvantages of solar power
Initial high investment
Unreliable due to weather
Cannot operate at night and less effective in winter
Energy transfers from n hydroelectricity
Rainwater is caught and allowed out through turbines, transferring energy from the gravitational potential energy store of the water to kinetic energy stores as it falls, which is used to generate electricity
