A Form of energy that is related to the K.E. of molecules. The motion of molecules produces heat. The more motion, the more heat is generated.

Heat Transfer

The movement of heat (thermal energy) from a warmer object to a colder one.

Heat is a moving energy.There are three forms of heat transfer:Conduction Convection Radiation

The transfer of heat by direct contact between objects or particles.

Heat transferred through space.

EXAMPLE: The sun’s rays causing a sunburn.

Heat transferred by the movement of molecules within a substance.

Movement occurs from warmer areas to cooler areas.

The movement of a substance that is caused by differences in temperature and density.

Examples: wind boiling water

Nature wants everything to be balanced !!!

Conductors are materials that transfer heat easily.

Examples: metals like copper and gold.

A pot is a conductor.

The molecules in a conductor are close together. This allows the heat to move to all parts of the pot and the stew in the pot.

An insulator is a material that does not transfer heat easily.

Examples: liquids and gases jackets pots handles

A cooler (a thermos) is an insulator.

The molecules in an insulator are far apart. This helps prevent heat from flowing in or out.

Thermal Equilibrium

Two bodies are said to be at thermal equilibrium if they are at the same temperature. This means there is no net exchange of thermal energy between the two bodies. The top pair of objects are in contact, but since they are at different temps, they are not in thermal equilibrium, and energy is flowing from the hot side to the cold side.

hot coldheat

26 °C 26 °C

No net heat flow

The two purple objects are at the same temp and, therefore are in thermal equilibrium. There is no net flow of heat energy here.

QuestionWhat type of heat transfer?

Warm air mass, bringing a change in the weather.

Wire getting hot from an electric appliance.

Heating a room with a fireplace.

Egg cooking in a frying pan.

Roof of a house becoming hot.