heat transfer

• heat: the thermal energy
• heat always moves from high to low temp
• thermal equilibrium: object at same temp
• the ways of heat transfer:

  1. conduction (solid)
  2. convection (liquid & gases)
  3. radiation (vaccum)
• conduction: the transfer of heat in solids through vibration without the transfer of matter
• why are metals good conductors?

  because metals have free moving electrons and the free electrons gain heat energy colliding and moving heat to other molecules
• good conductors:

  1. iron
  2. copper
  3. steel
• bad conductors:

  1. plastic
  2. rubber
  3. wood
  4. glass
• insulators:

  1. air
  2. vaccum
  3. water
• convection: transfer of heat thru liquids and gases
• as the temp of the molecules increases the density decreases which causes them to float
• convention current: as the less dense molecules move up the more dense molecules move down
• hot liquid is less dense

  cold liquid is more dense
• the amount of radiation depending on

  1. color
  2. temperature
• dark dull = best emittor and absorber
• shiny white = worst emitter and absorber