3657242352 by shuifanglj

VIEWS: 11 PAGES: 3

									                    HEAT TRANSFER VOCABULARY

Heat: is energy of motion
             is kinetic energy
                         Excited atoms
                         Movement of atoms
                              o Solids vibrate in place
                                     Jitter, wobble
                                     Atoms push apart = expand
                              o Liquids & gases bounce & move around
                                (linear)
                                     Hotter = faster motion, expand &
                                       push apart

Heat transfer:
     Rule: heat always moves from hotter to colder
     Heat moves in 2 ways:
            1.    Radiation
            2.    Conduction

Radiation: energy that is transmitted through space in rays, waves, or
      particles
                  Source is the Sun
                  Streams out in all directions
                  Travels through space until it hits an atom
                  Examples:
                             1. light            4. radio
                             2. X-rays 5. microwave
                             3. infrared 6. ultraviolet

Reradiated Energy:       energy that is radiated again
      Example:
         a. energy transfers from the Sun to the land or sea
         b. then from the land or sea back to the atmosphere
Differential Heating: different materials heat up at different rates
                different materials can store different amounts of heat
                Example:
                            o Water stores a lot of heat so it takes a long
                              time to raise its temperature
                            o Air stores only a little heat so it warms up
                              quickly

Conduction: the transfer of energy from one place to another by contact
             Heat/energy moves from molecule to molecule
             High energy molecule collides with a lower energy molecule
               and passes energy/heat to it
                  o “hotter” molecule
                                                  “cooler” molecule
                                The first molecule loses energy; it gets
                                  cooler
                                The second molecule gains energy; it gets
                                  hotter

               Example:
                   o Metal spoon in a pot of soup
                          Steel molecules in spoon receive energy by
                           contact with hot water molecules
                          Steel molecules “pass the message” or
                           heat/energy along to their neighbors by
                           conduction (contact)
                          Handle of the spoon gets too hot to hold
                           because energy/heat was conducted out to the
                           end
                          Heat transfers to your hand through contact
                          Your brain tells you to let go of the hot spoon!

								
To top