energy Flashcards
energy stores
kinetic energy store, gravitational potential energy store, elastic potential energy store, electrostatic energy store, magnetic energy store, chemical potential energy store, nuclear energy store, thermal energy store
kinetic energy
the energy of a moving object
gravitational potential energy
the energy something gains when you lift it up, and which it loses when it falls
elastic potential energy
the energy of a stretched spring or elastic band
electrostatic energy
the energy due to the force of attraction (or repulsion) between two charges
magnetic energy
the energy due to the force of attraction (or repulsion) between two magnets
chemical potential energy
the energy contained in a chemical substance
nuclear energy
the energy contained within the nucleus of an atom
thermal energy
the energy something has due to its temperature (or state)
energy transfers
mechanically, electrically, heating, radiation
mechanically (energy transfer)
when a force acts on a body, energy can be transferred between two stores
electrically (energy transfer)
electricity can transfer energy from a power source, delivering it to components within a circuit
heating (energy transfer)
thermal energy can be transferred from place to place by the process of conduction, convection and thermal radiation
law of conservation of energy
energy is not created or destroyed, it can only be used or transferred from one store to another
efficiency formula
useful energy output/ total energy output x100
gravitational potential energy formula
mass x gravitational field strength x height
relationship between work done and energy transferred
work done=energy transferred
work done formula
work done=force x distance
what is power
power is the rate at which energy is transferred or the rate at which work is done
power formula
power= work/time
kinetic energy formula
ke= 1/2 x mass x velocity2
thermal conduction
the transfer of thermal energy through a substance by the vibration of the atoms within the substance
convection
the transfer of heat through fluids by the upward movement of warmer, less dense regions of fluid
radiation
the transfer of energy by infrared waves
GPE
the GPE of an object will increase if we apply a force on it in the opposite direction to the pull of gravity
non-renewable resources of energy
- burning fossil fuels
- nuclear fuel
fossil fuels +-
+cheap
+ can generate large amount of electricity in a single location
- produces sulphur dioxide which causes acid rain
- non-renewable, cannot be replaced easily
- adds CO2 to the atmosphere
nuclear fuel +-
+ ‘clean’ it does not produce greenhouse gases
- nuclear power stations are expensive to build
- non-renewable
- accidents and problems with disposal of radioactive material
electricity generated in power stations
heat from nuclear fuel or burning fossil fuels is used to heat water. high-pressure steam is produced that makes the blades of a turbine spin. turbine is used to turn the generator (this generates the electricity)
renewable energy resources
- hydroelectric power
- wave energy
- wind power
- solar power
hydroelectric power
hydroelectric pjower station uses a turbine to turn the generators. these power stations use the stored GPE of water in high reservoirs built in the mountains, the GPE is transferred to KE as the water flows down the mountain to the power station below
hydroelectric power +-
+ clean
+ renewable
- building the reservoirs and power stations can spoil the landscape
- reservoir can destroy the natural habitat for wildlife
tidal power
generate power by turning turbines as the tide flows into a dammed river estuary- where a river joins the sea.
tidal power +-
+ renewable
+ more powerful than wind since water is denser
+ clean source of energy does not release greenhouse gases
- expensive
- dams might damage habitats for wildlife
wave energy
energy can be extracted from waves, the continuous movement of the surface of the sea and oceans is the result of a combination of tides and wind
wave energy +-
+ clean, produces no greenhouse gases
- Wave-powered generators do not work in calm water
- Wave-powered generators do not produce very much electricity
wind power +-
+ clean
+ land under wind turbines can still be used for farming
+ renewable
- lots of wind turbines are needed to produce useful amounts of electricity
- can cause noise pollution and may kill birds and bats
solar power
photovoltaic cells transfer light energy directly to electrical energy
solar power +-
+ renewable
+ don’t produce greenhouse gases
- only work when it is sunny
- expensive
- only 15% efficient
geothermal energy +-
+ renewable
+ does not produce pollution
- expensive
