heat
DESCRIPTION
Heat. By Neil Bronks. Expansion. 400 Kelvin (127 0 C). Atoms vibrate more at higher temperature. 200 Kelvin (-73 0 C). Zero Kelvin (-273 0 C). Expansion. This makes objects take up more volume. 400 Kelvin. 200 Kelvin. Zero Kelvin. Ball and ring. Proves solids expand when heated. - PowerPoint PPT PresentationTRANSCRIPT
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HeatHeat
ByNeil Bronks
ByNeil Bronks
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ExpansionExpansion Atoms vibrate more at higher
temperature Atoms vibrate more at higher
temperature
Zero Kelvin
(-2730C)
200 Kelvin
(-730C)
400 Kelvin
(1270C)
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ExpansionExpansion This makes objects take up more
volume This makes objects take up more
volume
Zero Kelvin
200 Kelvin
400 Kelvin
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Ball and ringBall and ring
Proves solids expand when heated
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SolidsSolids Expansion can damage railway
lines Expansion can damage railway
lines
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Expansion Joints on Bridges
Expansion Joints on Bridges
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Bi-Metallic StripBi-Metallic Strip
The bottom metal expands more than the top strip.
It bends! Used to control
Gas Oven
The bottom metal expands more than the top strip.
It bends! Used to control
Gas Oven
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Bi-Metallic StripBi-Metallic Strip
The bottom metal expands more than the top strip.
It bends! Used to control Gas Oven
The bottom metal expands more than the top strip.
It bends! Used to control Gas Oven
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LiquidsLiquids Use to measure temperature as
liquid expands up a tube Use to measure temperature as
liquid expands up a tube
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Gas Gas Expands a lot with a small
temperature rise Expands a lot with a small
temperature rise
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Heat TransferHeat Transfer
Conduction-Transfer
byvibrations
Radiation-Transfer by
Electro-magnetic wave
Convection- Hot air
risingcarrying
theheat up with it.
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ConductionConductionIn a solid every atom is physically bonded to its neighbours in some way.If heat energy is supplied to one part of a solid, the vibration travels through the solid.
Conduction is the transfer of energy through matter from particle to particle. It is the transfer and distribution of heat energy from atom to atom within a substance.
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Internet ConductionInternet Conduction
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Practical ConductionPractical Conduction
A spoon in a cup of hot soup becomes warmer because the heat from the soup is conducted along the spoon. Conduction is most effective in solids
It is also why stone and metals appear cold. They are just good conductors.
A spoon in a cup of hot soup becomes warmer because the heat from the soup is conducted along the spoon. Conduction is most effective in solids
It is also why stone and metals appear cold. They are just good conductors.
Chilly
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Water as a Poor Conductor
Water as a Poor Conductor
HEAT
The ice does not melt as the water is a terrible conductor and convection only works up.
Metal Gauze
ICE
Test Tube of water
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ConvectionConvection
Most houses have radiators to heat their rooms. This is a bad name for them - as they give off heat mainly by convection!
Most houses have radiators to heat their rooms. This is a bad name for them - as they give off heat mainly by convection!
The air expands and is less dense so it rises
It then cools and falls
CONVECTION CURRENT
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Internet exInternet ex
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Example of convection currentSea Breezes
Example of convection currentSea Breezes
HOT LAND WARM SEA
Day – On Shore
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Sea Breeze NightSea Breeze Night
COLD LAND WARM SEA
Night – Off Shore
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Ventilation with convection
Ventilation with convection
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Mine Ventilation DemoMine Ventilation Demo
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RadiationRadiation
The transfer of heat in the form of an electro-magnetic wave.
Only form of heat that can travel through a vacuum
The transfer of heat in the form of an electro-magnetic wave.
Only form of heat that can travel through a vacuum
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A silver or white body are good at holding and reflecting heat.
Black bodies are good at radiating and absorbing heat.
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InsulationInsulation
Vacuum stops heat loss by conduction and convection
Silver prevents heat loss by radiation
Vacuum stops heat loss by conduction and convection
Silver prevents heat loss by radiation
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Latent HeatLatent Heat
When something boils it takes in heat to change state
Its temperature does not rise.
Latent heat just changes state
When something boils it takes in heat to change state
Its temperature does not rise.
Latent heat just changes state
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Heating a solidHeating a solid
Temperature
Time
Melting point
Boiling point
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Heating a solidHeating a solidTemperature
Time
Boiling point
Melting point
Melting
Solid
Boiling
Liquid
GasHeat raises
temperature
Latent Heat Only
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SweatSweat Our sweat evaporates and takes
heat from our bodies Liquid sweat takes heat from skin as
it turns to vapour
Our sweat evaporates and takes heat from our bodies
Liquid sweat takes heat from skin as it turns to vapour
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Uses of Latent HeatUses of Latent Heat
Perspiration-Liquid evaporates to gas takes heat from our skin
Boiling or Melting matter Refrigeration-liquid boils to take
heat from food Heat Pumps- reverse of refrigerator Latent heat is heat that changes
state
Perspiration-Liquid evaporates to gas takes heat from our skin
Boiling or Melting matter Refrigeration-liquid boils to take
heat from food Heat Pumps- reverse of refrigerator Latent heat is heat that changes
state
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The FridgeThe Fridge
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The RefrigeratorThe Refrigerator
Compressor
Liquid GasLiquid boils and takes in Latent Heat from the food
Gas turns back into a liquid giving out heat
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SummarySummary
Conduction Convection Radiation
Particles vibrate and transfer their heat to the next particle
Particles move and bring their heat with them
Heat transferred without the need of a medium (waves)
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SummarySummary Water a poor conductor Black good emitter and absorber Silver and white a good reflector and
insulator Latent Heat is the heat lost or gained
as a material changes state – e.g. sweat
Expansion is the volume change in solids liquids and gases.
Water a poor conductor Black good emitter and absorber Silver and white a good reflector and
insulator Latent Heat is the heat lost or gained
as a material changes state – e.g. sweat
Expansion is the volume change in solids liquids and gases.
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H/WH/W
P336 1,2,5,7,8,9,10,11,12,13 P336 1,2,5,7,8,9,10,11,12,13