Chapter Eleven: Heat

11.1 Heat11.2 Heat Transfer

11.2 Heat transferHeat conduction is

the transfer of heat by the direct contact of particles of matter.

Conduction occurs between two materials at different temperatures when they are touching each other.

Where is the heat energy conducted to and from in this system?

11.2 Heat transferThermal equilibrium occurs when two bodies have the same temperature.

No heat flows in thermal equilibrium because the temperature is the same in the two materials.

11.2 Thermal conductors and insulators

Materials that conduct heat easily are called thermal conductors and those that conduct heat poorly are called thermal insulators.

Is a down coat a conductor or an insulator?

11.2 ConvectionConvection is the transfer of heat through the

motion of matter such as air and water.The hot water at the bottom of the pot rises

to the top and replaces the cold water.

11.2 ConvectionConvection is mainly what distributes heat throughout a room.

11.2 Thermal radiationHeat from the Sun is

transferred to Earth by thermal radiation.

All the energy the Earth receives from the Sun comes from thermal radiation.

The higher the temperature of an object, the more thermal radiation it emits.

11.2 Thermal radiationThermal radiation is also

absorbed by objects.The amount of thermal

radiation absorbed depends on the surface of a material.

Dark surfaces absorb most of the thermal radiation they receive.

Silver or mirrored surfaces reflect thermal radiation.

11.2 Heat transfer, winds, and currentsA thermal is a

convection current in the atmosphere.

When a surface, like a road absorbs solar radiation, it emits energy as heat.

The warmed air molecules gain kinetic energy and rise.

Colder air is forced aside and sinks.

11.2 Thermal radiationThere are giant convection currents in Earth’s atmosphere.

The global wind patterns and Earth’s rotation also cause surface ocean currents to move in large circular patterns.