p2 Flashcards
What tare the 8 energy stores?
- Thermal energy store.
- Kinetic energy store
- Gravitational potential energy store
- Elastic energy stores.
- Chemical energy stores
- Nuclear energy stores
- Electromagnetic energy stores- two objects will have energy in this store if they exert a magnetic force on each other.
- Electrostatic energy stores- two objects will have energy in this store if they exert an electrostatic force on eachother.
Conduction:
Conduction is where the vibrating particles of a substance transfer energy to neighbouring particles.
Convection:
Convection is where the energetic particles of a substance move away from hotter to cooler regions.
Work done also is
energy transferred (they mean the same thing)
What are the two types of way work can be done?
work can be done mechanically or electrically.
The conservation of energy says that:
Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed.
What happens when energy is transferred between stores?
When energy is transferred between stores, not all the energy is transferred usefully to the store that you want, some of it is dissipated. (Usually to the thermal energy stores of the surroundings.)
What measurement is energy usually measured in?
Energy is usually measured in Joules however for electrical devices it might be given in kilowatt-hours.
No device is ever…
…100% efficient, because whenever work is done, some of the energy transferred is always wasted. The less energy that is “wasted”, the more efficient the device is said to be.
Efficiency=
Useful energy transferred / total energy transferred.
How can the efficiency of any energy transfer increased?
The efficiency of an energy transfer can be increased by reducing the amount of unwanted energy transfer. An example of this might be lubrication on a motor.
How can you reduce energy loss in buildings?
To reduce the amount of energy lost in buildings you can use thermal insulation. For example: Loft insulation, thick curtains.
Also the thickness of wall determines the rate of energy transfer. So the thicker the walls the lower the rate of energy transfer
What do Sankey diagrams help show?
Sankey diagrams summarise all the energy transfers taking place in a process. The thicker the line or arrow, the greater the amount of energy involved.
What are the two types of energy resources?
Energy resources can either be renewable or non-renewable.
What type of energy resource do humans usually get their energy from?
Humans tend to get most of their energy from non-renewable sources, which means they will run out one day.
What are the 3 main fossil fuels on Earth?
The 3 fossil fuels are:
-Coal
-Oil
Gas
What is an advantage of using fossil fuels to generate energy?
An advantage of using fossil fuels to generate energy is that they are reliable and fast. Also the resources are extracted from the Earth at a quick enough rate to keep up with the demand from humans
What are the disadvantages of using fossil fuels?
A disadvantage of using fossil fuels is that they damage the environment when they’re used. They also contribute to the greenhouse effect as when they are burnt CO2 is released into the atmosphere, which results in an increase in global warming.
Renewable energy:
Renewable energy is one that will never run out. Most of them still do damage the environment but in a much less nasty way than non-renewable energy resources.
What are the main renewable energy resources?
The main renewable energy resources are bio fuels, wind, hydroelectricity and the tides.
How is power generated inside a power station?
- As the fossil fuel burns the water is heated.
- The water boils to form steam, which moves and turns a turbine.
- The turbine is connected to an electrical generator, which generates a potential difference across (and so a current through) a wire by spinning a magnet neat to the wire.
- The current produced by the generator flows through the national grid.
What is solar power?
Solar power is power obtained by harnessing the energy of the sun’s rays.
Where is solar power most often used?
Solar power is often used in remote places where there’s not much choice to power electric road signs and satellites. The initial costs are pricey however after that the energy is free.
What are bio fuels made up from?
Bio fuels are made from plants and waste and they are a renewable energy resource because we can just grow them.
