4. Energy Resources & Transfer Flashcards
What are the advantages and disadvantages of methods of large scale electricity production?
(Renewable/non-renewable sources)
Fossil fuels- Wind power- Solar power- Nuclear power- Burning wood-
Fossil fuels: non renewable; release CO2.
Burning wood: renewable; release CO2; destroy habitats.
Wind power: visual pollution; produces small amounts of electricity for space and effort in comparison to other methods.
Solar power: relies on the weather.
Nuclear power: dangerous; many waste products.
describe energy transfers involving the following forms of energy: thermal (heat), light, electrical, sound, kinetic, chemical, nuclear and potential (elastic and gravitational)
wind- the kinetic energy from the wind, turns a turbine which turns a generator which produces electrical energy
water- Kinetic energy from water, turns a turbine which turns a generator which produces electrical energy
geothermal resources- Thermal energy heats water, water turns into steam, the thermal energy of the steam turns a turbine which then has kinetic energy, the turbine turns a generator which produces electrical energy
solar heating systems- Light energy from the sun into thermal energy in water
solar cells-convert light energy from the sun into electrical energy
fossil fuels- Chemical energy is burnt to form heat energy, this turns into heat energy in water, this turns into kinetic energy in a turbine, this turns into electrical energy in a generator.
nuclear power- kinetic energy in uranium, heat energy in water, kinetic energy in turbine, electrical energy in generator.
What equation links power, work done (energy transferred), and time taken?
Power= work/time
What is ‘power’?
Power is the rate of work,
Power is also the rate of energy transfer.
So power is how quickly these processes are done.
how does conservation of energy produce a link between gravitational potential energy, kinetic energy and work?
The best way to explain this idea is with a swinging pendulum:
At the top of the swing, it will have its highest gravitational potential energy (as its further from the earth); but it will have its lowest kinetic energy (it slows to a stop at the top point).
At the bottom of the swing, it will have its lowest gravitational energy (as it is closer to the earth); but it will have its highest kinetic energy (it goes very quickly past the bottom point).
Between the points work (force x distance) is constantly being done: the pendulum is moving through space.
Remembering that work done is equal to energy transferred, we can see that as work is done that moves the pendulum upwards, kinetic energy is transferred in to gravitational potential energy. When work is done to bring the pendulum downwards, energy is transferred from GPE to KE.
The pendulum demonstrates that energy is conserved, as then energy is constantly changing between different forms. The only reason that energy is lost from the pendulum, and it slows down, is that some energy is transferred into heat or sound.
What equation links kinetic energy, mass, and velocity?
Kinetic energy=
Kinetic energy = 1/2 x mass x velocity(squared)
What equation links gravitational potential energy, mass, gravity, and height?
gravitational potential energy = mass × g × height
GPE = m × g × h
It may be useful to think that mass, gravity and height are all things that increase GPE.
What equation links work, force, and distance moved?
Work done= force x distance moved
How is insulation used to reduce energy transfers from buildings and the human body?
If something with heat energy is surrounded by an insulator, it wont lose heat by conduction. This is true in buildings where insulating materials are put in walls and on floors to stop heat being lost from inside. This is the same in humans where we wear clothes to stop heat being lost from conduction. Air is a poor conductor, so materials with many air gaps in are also poor conductors; air trapped between double glazing prevents heat loss through windows.
What is the role of convection in everyday phenomena?
Convection is helpful as it distributes heat energy. This is useful in many situations, for example, a radiator in one place will be able to heat a whole room, as hot air will rise away from it creating a current of cool air to be heated.
How does energy take place by…
Conduction?
Convection?
Radiation?
(Only heat energy)
Conduction is when energy is passed from one particle to another via contact. For example heat is passed from your skin to a window when they touch.
Convection is when particles with energy rise, the space they leave is filled by other particles. If the source of energy continues these new particles will also gain energy, they will then rise and the process will be repeated.
Radiation is when heat is transferred as infra red waves. These waves can travel through space and be conducted or reflected.
What equation links ‘useful energy output, total energy output, and efficiency’?
Efficiency = useful energy output / total energy output
describe energy transfers involving the following forms of energy: thermal (heat), light, electrical, sound, kinetic, chemical, nuclear and potential (elastic and gravitational)
Energy can change from one form to another. Some examples include:
Chemical energy in food turns into kinetic energy for movement;
Electrical energy in a circuit turns into heat energy in a resistor;
Kinetic energy in your muscles turns into sound energy from you voice.
Elastic potential energy in a taught rubber band turns into kinetic energy when it sails through the air.
