Energy Transfers Flashcards
(26 cards)
Energy transfers
Electrical Light Sound KE Nuclear Thermal GPE Elastic potential Chemical
Energy conservation
About using fewer resources to reduce damage to environment
Principle of the conservation of energy
Energy cannot be created or destroyed
Can only be transferred from 1 form to another
Only useful when transferred from 1 from to another
Efficiency
Energy transfers involve energy loss
Heat
Higher the lost energy, less efficient
Calculating efficiency
Useful output/total energy input =efficiency
Sankey diagrams
Figure out what 1 square is worth
Use that and width of arrow to find efficiency
Heat tansfer
Conduction, convection, radiation
Bigger temp difference, faster gets transfer
Conduction
Solids
Particles packed tightly
Vibrations cause others particles to collide
Extra KE passed through solid, causing rise in temp at other side of solid
Transfer of heat energy by particles
Convection
Liquids and gases
Heat energy transferred from heater to water by conduction
Particles near coil get more KE, move faster
More distance between them, water expands, less dense
Reduction in density, rises above cooler water
Hot water displaces cold water, cold sinks towards heater
Cold water heated and rises
Best in rounded or squarish containers
Transfer of energy through particles
Thermal radiation
Emission of infrared radiation
All objects emit and absorb heat radiation
Hotter than surroundings, emits more
Colder than surroundings, absorbs more
Surfaces in thermal radiation
Matt, best absorbers, emitters
Shiny, worst absorbers, emitters
Black, best
White, worst
Black and white
Black, SSA:V
White, LSA:V
Reducing energy transfer in the house
Loft insulation Hot water tank jacket Double glazing Thick curtains Cavity wall insulation Draught proofing
Loft insulation
Conduction
Convection
Fibreglass wool on loft and ceiling floor
Hot water tank jacket
Conduction
Radiation
Fibreglass wool
Double glazing
Conduction
Convection
Trap air
Air, poor conductor
Thick curtains
Conduction
Radiation
Cavity wall insulation
Conduction
Convection
Foam
Air pockets, poor thermal conductors
Draught proofing
Convection
Foam and plastic around doors, stop draughts blowing in
Human heat transfer
Hairs stand on end to trap thick layer of insulating air around body, limits convection
Clothes trap air, reduce heat transfer by conduction and convection, radiation
Water energy transfers in generating electricity
KE from water
Turns turbine
Turns generator
Electrical
FF generating elctrictiy
Chemicals burnt
Heat energy in water
KE in turbine
Elec in generator
Geothermal generation of energy
Thermal heats water Water, steam Steam turns turbine KE Turns generator Electrical
Nuclear generation of electricity
KE in uranium
Heat energy in water
KE in turbine
Electrical generator
