Energy Resources and Transfer Flashcards
What’s potential/chemical energy
Gravitational potential, elastic potential, chemical energy are forms of stored energy because the energy isn’t doing anything, only waits to be turned into another form.
Conservation of energy:
Energy can never be created or destroyed, only transferred from one form to another.
Examples of electrical, nuclear, gravitational potential energy:
Electrical: whenever a current flows
Nuclear: released only from nuclear reactions
Gravitational potential energy: possessed by anything which can fall
Energy always ends up as…
Heat/thermal energy.
Archer/bow energy transfers:
Chemical ➡️ elastic potential (pulling back)
(Letting go) elastic potential ➡️ kinetic
(Heat and sound also)
How does conduction happen?
Conduction of heat is the process where vibrating particles pass on their extra kinetic energy to neighbouring particles. (Mainly in solids)
How does radiation happen?
Transfer of heat by electromagnetic waves. Emission of thermal radiation occurs in solids, liquids, gases. Bigger the temp difference, faster heat is transferred between body and surroundings.
Doesn’t rely on particles- can happen in vacuums
How does convection happen?
Convection occurs when the more energetic particles move from the hotter region to the cooler region - and take their heat energy with them.
Explain convection currents in every day phenomena
Immersion heater - heat energy transferred from heater coils to water by conduction (particle collision)
Particles near coils get more energy, move faster so there’s more distance between them- the water expands and becomes less dense.
Hotter less dense water tends to rise above the cooler dense water. And moves the cooler water away to sink towards the heater cools.
Cold water heated by coils, rises. Convection currents, circulating heat energy through the water.
Same with air with a radiator!
(They’re all about changes in density)
Where is convection most efficient?
In roundish, squarish containers because they allow the convection currents to work best.
No - shallow, wide/ tall,thin containers
How do humans reduce heat transfer
In cold, hair on skin stands up to trap a thicker layer of insulating air around body. Limits heat loss by convection, conduction as airs an insulator (particles are spread out)
Clothes - pockets of air trapped between layers reduce by convection, conduction, radiation - material absorbs some heat radiated out by our bodies.
Loft insulation stops heat loss in the home:
Thick layer of fibreglass wool on loft floor - conduction (airs an insulator) convection (convection currents can’t be made- fibres trap air- no space), radiation (absorbs heat)
Cavity wall insulation stops heat loss in the home:
Foam squirted into gap between bricks - conduction (airs an insulator- air pockets in foam trap air) convection (convection currents can’t be made), radiation (absorbs heat)
Draught-proofing stops heat loss in the home:
Strips of foam and plastic around doors and windows stop draughts of cold air being blown in. (Convection)
Hot water tank jacket stops heat loss in the home:
Lagging such as fibre glass wool -conduction, radiation
Double gazing stops heat loss in the home:
Two layers of glass with a narrow air gap between - reduce conduction (airs an insulator) convection (gap too small to allow air to circulate)
Thick curtains stops heat loss in the home:
Big bits of cloth over the window to reduce heat loss by conduction (insulator) and radiation (absorb the heat)
When a force moves on an object…
Energy is transferred and work is done
Work done is equal to energy transferred (both joules)
When you do work against friction, most of energy is transformed into heat, some into sound. Generally “wasted” energy
understand how conservation of energy produces a link between gravitational potential energy, kinetic energy and work:
When falling, gpe is converted into KE.
KE gained = GPE lost
work is being done while energy is being transferred
(KE ➡️ GPE, GPE ➡️ KE)
What’s power?
The rate of transfer of energy/rate of doing work
Advantages of fossil fuels (coal, oil, gas):
- release a lot of energy, relatively cheaply
- doesn’t rely on weather- reliable
- lots of fossil fuel power stations already, don’t need to spend on new technology to use them
Disadvantages of fossil fuels (coal, oil, gas):
- releases CO2 into the atmosphere when burned in power stations - contributes to global warming
- releases SO2 which causes acid rain. Harms trees, soils, huge impact on wild life
- non renewable - eventually gonna run out
Non renewable resources:
Fossil fuels (coal, oil, gas), nuclear fuels (uranium, plutonium)
Disadvantages of nuclear fuels:
- Nuclear reactors are expensive to build and maintain, take longer to start up that fossil fuel ones
- processing uranium before using it causes pollution.
- Risks of leaks of radioactive material
- when old and efficient, need to be decommissioned (shut down and made safe) which is expensive
