Heating and Cooling

Heating and Cooling

1. Condensation

   • A liquid can freeze or a gas can condense if it loses enough heat energy.

2. Changes of State

   • A solid can melt or a liquid can evaporate or boil if it gets enough heat energy.

3. Temperature

   • Temperature is an important measurement.
     • Temperature tells us how hot or cold something is.
     • Temperature is measured with a thermometer.
     • Temperature is measured in degrees Celsius.

4. Heat Transfer

   • Depend on transfer of heat energy.
     • Heat energy is measured in joules.
     • Heat energy transfers from hot to cold.
     • Heat transfer happens in three ways.
       • Conduction is the method of heat transfer in solids.
         • Metals are good thermal conductors.
         • Non-metals like plastic, and particularly air, are poor thermal conductors.
           • Poor thermal conductors are called thermal insulators.
       • Convection happens in liquids and gases.
         • Hot liquid or gas rises up through colder liquid or gas.
       • Heat radiation carries heat energy across empty space at high speed.
         • Shiny white surfaces are poor absorbers and good reflectors of radiated heat.
         • Heat energy reaches the Earth from the Sun by this method.
         • Dull black surfaces are good absorbers of radiated heat.