Physics 1 - Heat (thermal energy)

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  • Created by: Ls
  • Created on: 17-05-14 12:09
brownian motion (3)
smoke particles 'jiggle', they are being constantly hit by fast moving air particles, change direction each time they are hit
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kinetic theory (2)
everything is made of particles which are always moving/vibrating, used to explain properties of matter: expansion, change of state and diffusion
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heat transfer
heat always moves from hot to cold; conduction, convection, radiation
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conduction (2)
heat travels from atom to atom; occurs in solids: particles vibrate when heated and pass the kinetic energy when they touch other particles
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metals (conduction)
good conductors because of free-moving electrons, which travel through the metal, transferring the energy more quickly
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gases and liquids (conduction) (3)
most liquids are poor conductors of heat; gases are very poor conductors; air is an insulator: has no free electrons
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convection (2)
when fluids are heated, they expand, become less dense and rise carrying heat, cold fluids replace hot fluids and a convection current is created
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thermals
rising hot air, keeps a glider up in the air because it creates a force on the glider
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convection current
caused by molecules gaining more energy when hot
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radiation (3)
transfer of energy by electromagnetic waves, heat can travel by infra red radiation and can travel through a vacuum
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emitting radiation
something is hot and likely to cool down (better emitters cooll down faster) : silver>white>...>glass black>matt black
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absorbing radiation (2)
something in a hot place and likely to heat up (better absorbers heat up faster) : silver>white>...>glass black>matt black; better reflectors heat up more slowly: silver>white>...>glass black>matt black
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greenhouse effect
sun rays have short wavelength, gets through greenhouse gases and absorbed by Earth, it gets warmer and radiates Infra-Red rays with longer wavelength but can't get radiated out because Earth is not as hot as the sun
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expansion (3)
as objects get hotter, they expand (pushing forces) and when they cool down, they contract (pulling forces); liquids expand more than solids but less than gases
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evaporatio (in our body) (3)
a liquid in our body takes energy from it to change state by evaporation; faster (hot) molecules leave and slower (cold) ones stay behind until our body warms them; when we sweat, it takes latent heat from our body and evaporates
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evaporation depends on...
temperature, dryness of the air, wind and surface area
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latent heat
the energy needed from particles to change state without them actually changing temperature
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rate of thermal energy
depends on: shape, dimensions, mass, material, what the object is in contact with and the temperature difference between an object and its surroundings (bigger the faster)
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Other cards in this set

Card 2

Front

everything is made of particles which are always moving/vibrating, used to explain properties of matter: expansion, change of state and diffusion

Back

kinetic theory (2)

Card 3

Front

heat always moves from hot to cold; conduction, convection, radiation

Back

Preview of the back of card 3

Card 4

Front

heat travels from atom to atom; occurs in solids: particles vibrate when heated and pass the kinetic energy when they touch other particles

Back

Preview of the back of card 4

Card 5

Front

good conductors because of free-moving electrons, which travel through the metal, transferring the energy more quickly

Back

Preview of the back of card 5
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