What happens to the particles in a liquid or a gas when you heat them?
The particles spread out and become less dense.
A liquid or gas.
It is the way in which particles in a GAS or LIQUID move upwards, carrying heat with them
Think about when you boil water, the bubbles move upwards
Or think of a gas heater in the room, the heat rises around the room
Hot water rises
Cooler water sinks
Cools at the surface
Where is the cooling compartment put in a fridge?
It is put at the top, because cool air sinks, so it cools the food on the way down.
It is warmer at the bottom, so this warmer air rises and a convection current is set up.
Why are boilers placed beneath hot water tanks in people’s homes?
Hot water rises.
So when the boiler heats the water, and the hot water rises, the water tank is filled with hot water.
Why does hot air rise and cold air sink?
Cool air is more dense than warm air, so the cool air ‘falls through’ the warm air.
The temperature of an object tells us how HOT it is
Measured in degrees Celsius - °C
It is NOT the same as heat energy although the two quantities are related. e.g. a beaker of water at 60 °C is hotter than a bath of water at 40 °C BUT the bath contains more joules of heat energy
If an object has become hotter, it means that it has gained heat energy.
If an object cools down, it means it has lost energy
Heat energy always moves from:
HOT object COOLER object
e.g. Cup of water at 20 °C in a room at 30°C - gains heat energy and heats up – its temperature rises
Cup of water at 20 °C in a room at 10°C loses heat energy and cools down – its temperature will fall.