Heat Flashcards
What happens when we heat a solid,liquid or gas?
It expands
Heat.?
Is a form of energy.
What happens when we cool a solid,liquid or gas?
It contracts (gets smaller)
Heat transfer ?
Heat is transferred by 3 methods :
•Convection
•Conduction
•Radiation
Conduction
Heat travels from particle to particle along a substance, normally a solid.
Convection
Heat travels through a fluid (liquid or a gas) when the particles move and carry the heat.
Radiation
Heat travels from a hot object without the need for a medium, does not need a solid, liquid or gas to go through, will flow through a vacuum.
Conductor
Somethings that allows energy e.g. Heat to flow through it. E.g. Metal is a good conductor.
Insulator
A insulator is a substance that doesn’t allow to heat to flow through it easily. E.g. Plastic .
To show that a solid expands when heated and contracts when cooled?
Ball and ring apparatus .
Water?
Water begins to expand when cooled below 4 degrees C
Air?
Is a good insulator, keeps animals warm, is trapped by the fur and helps to insulate the animals.
Layers?
The hairs on our arms are not very good at keeping us warm, if we ware layers clothes, air is trapped to keep us warm
Winds are formed by Convection
The sun heats the earth. This causes hot air to rise . As the hot air rises it cools and then sinks down to the ground.
Temperature?
A measure of how hot an object is.
Thermometer
The liquid in a thermometer will expand and rise when heated and will contract and fall when cooled.
Boiling and freezing points of water?
Boiling = 100°C
Ice =0°C
Melting point
When a solid turns to a liquid
Boiling point
When a liquid turns to a gas
Freezing point?
When a liquid turns to a solid
Condensation?
When a gas turns to a liquid
Evaporation?
When a liquid turns to a gas
A kettle will normally boil at 100°C but with boil at 70°C on top of Mt.Everest?
Atmospheric pressure is less so it is easier for the water vapour to escape.
Latent heat?
The heat taken in or given out when a substance is changing state without a change in temperature.
Latent heat of fusion?
Is used when a solid changes to a liquid
Latent heat of vaporisation.
When a liquid changes to a gas
Dull,black surface radiates?
Heat better than a shiny surface
Dhll, black surface absorbs ?
Heat better than a shiny surface
When water is below 4°
It begins to expand
The amounts of heat in a substance depends on?
Temperature, mass and what it is made of e.g. 200ml of water at 60°C has twice as much heat as 100ml of water of 60°C
