Thermal Energy Transfer  Thermal Energy can be transferred by three methods Conduction Convection Radiation

Conduction  Conduction is the transfer of thermal energy by contact between particles of matter from a high temperature to a low temperature  Heat moves faster through solids and liquids This is because the particles are closer together

Convection  Convection is the transfer of thermal energy by the partcles of a fluid Fluids are liquids and gases Currents transfer heat from high temperature to low temperature As a fluid heats up it expands and becomes less dense This heated fluid will then rise above fluid of a lower temperature

Radiation  Radiation is the transfer of energy by electromagnetic waves It can travel through space where there is no matter This is radiant energy

Radiation  Materials can absorb, reflect, or transmit radiation Dark colors absorb radiation Light colors reflect radiation

 Radiation can pass through the particles that make up solids liquids and gases

Insulators  An insulator is a substance that heat flows slowly through  They will have a high specific heat  Gases make good insulators because they do not conduct heat well

Using Heat  On of the most basic ways of using heat is to heat your home  Most homes used a forced air system that pumps warm air into a room and heat the room by convection

Radiators  Older buildings may use radiators  A radiator uses steam to heat rooms by convection

Thermodynamics  You can increase the thermal energy of an object with out adding heat  Thermodynamics is the study of the relationship between thermal energy, heat, and work

1 st Law of Thermodynamics  The increase in thermal energy of a system equals the work done on the system plus the heat transferred to the system

2 nd Law of Thermodynamics  It is impossible for heat to flow from a cool object to a warmer object unless work is done.  If you hold ice in your hand, heat flows from you to the ice cube

Engines  Heat can be converted into work  A heat engine is a device that turns heat into work  It is impossible to make an engine that completely converts heat into work  This is because it will violate the second law of thermodynamics