Energy Stores and Transfers Flashcards
What is the formula for gravitational potential energy?
Gravitational potential energy = mass x gravity x height
Egp = mgh
J = kgN/kgm
What is the formula for kinetic energy?
Kinetic energy = 1/2 x mass x velocity^2
Ek = 1/2mv^2
J = 1/2kgm/s
What is efficiency?
The amount of useful output of something compared to the wasted output
What is the formula for efficiency?
Efficiency = (Useful energy out (J) / Total energy in (J)) x 100
What is a sankey diagram?
A diagram showing the efficiency of a device by showing input energy and its useful and wasted output energy
What are the three types of heat energy transfer?
Conduction - particles bumping together and transferring energy to each other
Convection - fluid particles being heated, rising, cooling, sinking, and being heated again
Radiation - infrared radiation being emitted out by all objects with heat
What are advantages and disadvantages of renewable energy resources?
They will never run out. They damage the environment, but less badly than non-renewables. They do not provide much energy and some are unreliable.
What has been the trend in the UK’s energy use?
Over the 20th century electricity use rapidly increased. Since the start of the 21st century it has been slowly declining from more efficient appliances. Most of our electricity comes from fossil fuels and nuclear power. We are trying to increase use of renewable energy sources.
What are the types of energy?
Magnetic Kinetic Heat (Thermal) Light Gravitational potential Chemical Sound Elastic potential Electrostatic Nuclear Most Kids Hate Learning GCSE Energy Names
What is conservation of energy?
Energy can be stores, transferred between stores, and dissipated, but it can never be created or destroyed. In a closed system energy has no net change.
How can energy be transferred between stores?
Mechanically - forces doing work
Electrically - charge doing work against resistance
By heating
By radiation
How does lubrication help increase efficiency?
When something, friction acts against it, wasting energy as heat. Lubricants coat objects touching each other, reducing friction so increasing efficiency.
How does insulation help?
Materials with lower thermal conductivities transfer heat poorly by conduction. Walls are made of low thermal conductivity materials to slow energy transfer through them. Some houses have cavity walls, with an air gap, as air conducts heat very poorly. Thicker walls also slow energy transfer rate.
What are the advantages and disadvantages of using fossil fuels?
They are reliable. Plants can respond quickly to changes in demand. Plants are cheap to build and run.
They are running out. They release CO2, contributing to global warming. Coal and oil can release SO2, causing acid rain. Oil spillages damage the environment.
What are the advantages and disadvantages of using nuclear energy?
It is reliable and can respond to demand. It does not produce CO2 and other pollutants.
Plants are expensive to build and safely decommission. Nuclear waste is dangerous and difficult to dispose of. There is a risk of meltdowns.
How do bio-fuels work?
They are created from plant products or animal waste. They can be burned to produce electricity or run cars. They are supposedly carbon neutral and can be grown fairly quickly. It is expensive to refine them and food crops may be burned instead. Some forests have been cleared to grow them.
How does wind power work? What are the advantages and disadvantages?
There are generators in each turbine. Wind turns the blades, rotating the generator and producing electricity.
There is no pollution and low running costs.
The initial cost is quite high, they do not produce much power individually, they can spoil the view and be noisy, and they only work when it is windy.
How does solar power work? What are the advantages and disadvantages?
Solar cells are made from materials that use energy from light to create a current.
It can be used in remote places such as deserts, there is no pollution, there are almost no running costs, they can be put on homes.
They use quite a lot of energy to make, they do not work as well in cloudy countries, and they do not work at night.
How does hydro-electricity work? What are the advantages and disadvantages?
A valley is flooded and a dam is built. Rainwater is caught and allowed out through turbines.
There is no pollution, production can be increased in times of high demand, and there are minimal running costs.
The environment is impacted in the valley and initial costs are high.
How do tidal barrages work? What are the advantages and disadvantages?
They are big dams build across river estuaries with turbines. As the tide comes in the estuary fills up, and water is let out through turbines at a controlled speed.
There is no pollution, it is quite reliable, and running costs are minimal.
Boat access is affected, they can spoil the view, they alter wildlife habitats, and initial costs are quite high.
What limits the use of renewable energy sources?
Building new plants is expensive. People often do not want new plants near them. Some resources are not as reliable as fossil fuels.
