energy Flashcards
What is energy?
The ability or capacity to do work
What is kinetic energy?
Energy an object has because it is moving
What is chemical energy?
Energy found in foods, fuel and batteries
What is thermal energy?
Energy stored in an object because of its temperature
What is gravitational potential energy?
Energy an object has due to its position above the ground
What is elastic potential energy?
Energy an object has because it has been deformed or stretched
What is electrostatic energy?
Energy due to the force of attraction/repulsion between two charged objects
What is magnetic energy?
Energy due to the force of attraction between two magnets
What is nuclear energy?
Energy contained within the nucleus of an atom
What is the law of conservation of energy?
Energy cannot be created or destroyed (only transferred)
What is useful energy?
Energy transferred to where it is wanted and in the form it is wanted (e.g., sound from a TV)
What is wasted energy?
Energy that is not usefully transferred (e.g., sound from an engine vibrating)
Why can energy efficiency never be above 100%?
You can’t get more energy out of a system than is put in
How can friction be prevented to avoid wasted energy?
Lubricating moving parts
How can air resistance be reduced to minimize wasted energy?
Streamlining the shapes of moving objects
How can sound be reduced to minimize wasted energy?
Tightening loose parts to avoid vibration
How can the resistance of a wire be reduced to cut down on wasted energy?
Use a wire with little electrical resistance
What is power?
The rate at which energy is transferred
What is conduction?
When particles closer to a heat source vibrate faster, get warmer and transfer energy to neighbouring, cooler particles
What is thermal conductivity?
The rate at which a material conducts thermal energy
What are insulators?
Materials that have low thermal conductivity
Why are metals good heat/electrical conductors?
They have delocalised electrons which are free to move between atoms and can carry charge
How does thermal energy from the sun travel to Earth?
Infrared waves
What is a perfect black body?
A theoretical object that absorbs all radiation that hits it
What is specific heat capacity?
How much thermal energy is required to raise the temperature of 1 kg of a substance by 1 degree Celsius
What is specific latent heat?
The amount of energy needed to change the state of 1 kg of substance without changing the temperature
What is specific latent heat of fusion?
The amount of energy required to melt (or freeze) a substance at its melting point
What is specific latent heat of vaporisation?
The amount of energy required to boil (or condense) 1 kg of substance at its boiling point
How does loft insulation reduce the rate of energy transfer?
Fibreglass (which has a low thermal conductivity) has air trapped inside, which reduces the rate of energy transfer by conduction
How does double glazing reduce the rate of energy transfer?
Air trapped between the 2 panes of glass acts as an insulator and reduces heat loss by conduction
How does cavity wall insulation reduce energy transfer?
The space between 2 layers of brick is pumped with insulation (which is a better insulator than the air it replaces) reduces heat loss by conduction
What are 3 advantages of fossil fuels as a source of energy?
- Cheap
- Easy to find
- Easy to transport
What are 3 disadvantages of fossil fuels as a source of energy?
- Non-renewable: will run out eventually
- Release atmospheric pollutants when burnt
- Release sulfur dioxide, which causes acid rain
What are 2 advantages of nuclear energy sources?
- Small amounts of fuel generate lots of energy
- Does not give off atmospheric pollutants
What are 2 disadvantages of nuclear energy sources?
- Non-renewable: will eventually run out
- Nuclear waste is toxic and is expensive to be stored
What is an advantage of biomass as an energy source?
Cheap and readily available; if replenished, it can be sustainable
What are 2 disadvantages of biomass as an energy source?
- When burnt, gives off atmospheric pollutants
- If crops aren’t replenished, is not renewable
What are 2 advantages of solar as an energy source?
- Potentially infinite supply
- Singly dwellings can have their own electricity supply
What are 2 disadvantages of solar as an energy source?
- Implementing solar panels can be expensive
- Unreliable as weather must be sunny to generate energy
What are 2 advantages of wind as an energy source?
- Potentially infinite supply
- Does not release atmospheric pollutants
What are 2 disadvantages of wind as an energy source?
- Implementing wind farms can be expensive
- Wind farms cause visual and noise pollution
What are 2 advantages of tidal as an energy source?
- Ideal for islands like the UK
- Potentially infinite supply
What are 2 disadvantages of tidal as an energy source?
- May have a negative impact on sealife
- Tidal barrage construction is expensive
How is geothermal energy generated?
Comes from energy released by radioactive substances deep within the earth, which is transferred by heating towards the earth’s surface
How does hydroelectricity generate energy?
Rainwater, collected in a reservoir, flows downhill. The flowing water drives turbines that turn electricity generators at the bottom of the hill
