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08/04/23
Heating and CoolingHeating and Cooling
08/04/23
Heat and TemperatureHeat and Temperature
This cup of coffee will ____ ____ because it is _____ ____ heat energy into the surroundings.
This drink (taken out of the fridge) will _____ ___ because it is _____ ___ heat energy from the surroundings.
Heat is a type of energy that will flow from a warm area to a colder one. For example…
Words – giving out, warm up, taking in, cool down
08/04/23
Heat energyHeat energyHow much heat energy an object has depends on its temperature AND how much of it there is…
The sparkler is at a higher temperature than the bath, but the bath is MUCH heavier, so it has more heat energy.
08/04/23
Particle theory revisionParticle theory revisionParticle theory is all about explaining the properties of solids, liquids and gases by looking at what the particles do.
In a solid the particles ______ around a _____ position. There is a ______ force of attraction between each particle and they are very _____ together
SOLIDS
Words – strong, close, vibrate, fixed
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08/04/23
LIQUIDS
GASES
In a liquid the particles are _____ together but can move in any direction. They won’t keep a _____ shape like _____ do.
In a gas the particles are very far apart and move _____ in all directions. They often ______ with each other and because they are far apart they can be easily _______.
Words – fixed, collide, quickly, close, very, solids
08/04/23
Heating a solidHeating a solidWhen a solid is heated it expands. We can use particle theory to explain why:
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When a solid, liquid or gas heats up it will expand.
When a solid, liquid or gas cools down it will contract.
08/04/23
Changes of stateChanges of state
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08/04/23
Changes of StateChanges of StateWhat are these processes called? Choose from freezing, evaporating, melting, condensing
08/04/23
Heating iceHeating ice
150
100
50
0
-50
Temp/OC
Time/sThis flat line shows where energy is being used to break bonds – this has to be done during melting
This flat line shows where energy is being used to push the particles further apart for evaporation
08/04/23
ConductionConduction
CONDUCTION is when heat moves through a ________. Metals are better conductors of heat than plastic or wood. This is why…
These parts are made of plastic or wood:
These parts are made of metal:
08/04/23
ConductionConduction
In this experiment we saw that liquid water is a poor conductor of heat. The ice cube did not melt even though the water above it was boiling.
Air is also a poor conductor of heat. This is how many types of house insulation and clothing keep us warm.
08/04/23
RadiationRadiationWhen you wear a black t-shirt on a hot, sunny day you would feel ______ than if you wore white. This is because black ________ infrared radiation (i.e. heat) from the sun better than white does.
Conduction is when heat travels through a solid and convection happens in a liquid or gas, but radiation can happen through absolutely ________ because the heat is moving by ______. This is how heat reaches us from the ____.
I’m very hot!I’m cool!
Words – sun, absorbs, nothing, warmer, waves
08/04/23
ConvectionConvectionConvection is all about when a gas or liquid (“fluid”) moves and carries heat with it. When the fluid is heated it ____________. This means that it will become less __________ than the colder fluid around it. Because of this the warmer fluid will try to “_______” over the colder fluid, and this is why warm air rises. This is called a convection ___________. This is how heat reaches us from the ___________ in this room.
Words to use: expands, radiators, dense, heated, current, float
Heat transferHeat transfer1) Conduction – this is when heat is passed on through a solid by vibrations of particles:
2) Convection – this is when “heated stuff” moves somewhere else and takes heat with it:3) Radiation – this is when heat is moved by “heat waves” (infra-red) – this is how heat reaches us from the sun:
08/04/23
EvaporationEvaporationHeat can also be lost when water evaporates (this is how we cool off when we sweat):
This water will evaporate because the water molecules have enough energy to “escape” from the rest of the water. When they do so they will take heat with them.
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