physics p2, energy resources and energy transfer Flashcards
9 types of energy- CLENT KEGS
1- CHEMICAL 2- LIGHT 3- ELECTRICAL 4- NUCLEAR 5- THERMAL 6- KINETIC 7- ELASTIC POTENTIAL 8- GRAVITATIONAL POTENTIAL 9- SOUND
what are chemical and potential forms of?
stored energy
what’s the principle of the conservation of energy?
energy can never be created nor destroyed- it’s only ever transferred from one to another
efficiency=
useful energy output/ total energy input
no device is 100% efficient and…
…the wasted energy is always dissipated as heat
electrical devices convert ELECTRICAL ENERGY->
sound
light
heat
batteries convert CHEMICAL ENERGY->
electrical-> kinetic, heat, sound, light
GPE and ELASTIC POTENTIAL always get converted into ->
KINETIC ENERGY
how can heat be transferred?
by radiation, conduction or convection
what is thermal radiation the transfer of?
heat energy by electromagnetic waves- objects are continually absorbing and emmiting heat radiation. an object that’s hotter than its surroundings emits more radiation than it absorbs and vice versa
what is conduction?
in a solid: the process where vibrating particles pass on their extra kinetic energy to neighbouring particles. the vibrations are passed on to the near by aprticles
what is convection?
where more energetic particles move from the hotter region to the cooler region- and take their heat energy with them
how does an immersion heater work?
1) heat energy is transferred from the heater coils to the water by conduction
2) the particles near the coils get more energy so move faster- more distance between them so water expands and becomes less dense
3) this reduction in density means that hotter water tends to rise about the denser, cooler water
4) as the hot water rises it displaces the colder water making it sink to the heater coils.
5) this cold water is then heated by the coils and rises-cycle is continuous. you end up with convection currents going up round and down, circulating the heat energy through the water
where is convection most efficient?
in roundish or squarish containers- allow convection currents to work best
convection currents=
change in density
radiator convection=
hot, less dense air rises- displaces cooler air, cooler air flows to replace it