Physics Section 4: Energy Resources and Energy Transfer (COMPLETED) (D…
Physics Section 4: Energy Resources and Energy Transfer (COMPLETED)
Energy Resources and electricity generation
rely on weather
low electricity to space ratio
HEP (Hydro electric power)
can damage fish/ water life
expensive to set up
energy transfers- generation
kinetic energy in uranium, heat energy in water, kinetic energy in turbine, electrical energy in generator.
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.
convert light energy from the sun into electrical energy
Light energy from the sun into thermal energy in water
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
Kinetic energy from water, turns a turbine which turns a generator which produces electrical energy
the kinetic energy from the wind, turns a turbine which turns a generator which produces electrical energy
Work and Power
Power= work/ time
So power is how quickly these processes are done.
Power is also the rate of energy transfer.
Power is the rate of work,
Conservation of energy (GPE and KE)
The best way to explain this idea is with a swinging pendulum:
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.
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.
Between the points work (force x distance) is constantly being done: the pendulum is moving through space.
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).
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).
KE= 1/2 × m × v²
Kinetic energy = 1/2 x mass x velocity²
GPE = m × g × h
gravitational potential energy = mass × g × height
Work done and energy transferred are always the same.
W = F × d
work done = force × distance moved
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.
This is the same in humans where we wear clothes to stop heat being lost from conduction.
in buildings where insulating materials are put in walls and on floors to stop heat being lost from inside.
If something with heat energy is surrounded by an insulator, it wont lose heat by conduction.
An insulator is something that is bad at conducting.
Radiation is when heat is transferred as infra red waves. These waves can travel through space and be conducted or reflected.
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.
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.
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.
a light bulb wants to create light energy, but it creates heat at the same time.
The more energy that comes out as useful, the more efficient the object is.
With all devices that aim to use energy for a reason, some of the energy put in to run it comes out as a non useful form of energy.
useful energy output / total energy input= efficiency
conservation of energy
For example, when you switch on a light, you are not loosing energy from a battery (chemical), you are just converting it to light energy!
Energy will always carry on, just in a different form.
Energy can never be lost, only transferred.
Elastic potential energy in a taught rubber band turns into kinetic energy when it sails through the air.
Kinetic energy in your muscles turns into sound energy from you voice.
Electrical energy in a circuit turns into heat energy in a resistor;
Chemical energy in food turns into kinetic energy for movement;
Energy can change from one form to another, and frequently does.