Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Is heat kinetic energy

  1. Nov 16, 2004 #1
    Is heat kinetic energy, or is it a byproduct of kinetic energy, very much like light is a byproduct of electricity running through a bulb?, so heat would be the byproduct of running kinetic engergy across a surface with friction.
     
  2. jcsd
  3. Nov 16, 2004 #2

    Integral

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Actually temperature is a measure of kinetic energy. Heat is a little trickery to get a handle on. It can be seen as the transfer of that molecular kinetic energy from one location to another.
     
  4. Nov 16, 2004 #3
  5. Nov 16, 2004 #4

    krab

    User Avatar
    Science Advisor

    Heat is disorganized energy.
     
  6. Nov 16, 2004 #5
    when something is giving off heat it's givin off infrared right, well is it possible that one photon of the right frequency excites an atom to a given orbital and then goes back to ground state, and thus giving off a photon of the same frequency, in this case in the infrared range, or heat, and that passes it on to the next atom and such, which repeats the motion up untill it shoots it off into the outside, would that be classified as a transfer of heat, and how do you go from heat of friction, and apply it to the infrared part of the spectrum?
     
  7. Nov 16, 2004 #6
    hmnn

    but is it kinetic engergy then?
     
  8. Nov 16, 2004 #7

    DaveC426913

    User Avatar
    Gold Member

    "...when something is giving off heat it's givin off infrared..."

    This is something I've never quite understood.

    IR is a band of electromagnetic frequency.
    Heat is the kinetic energy of atoms. ANY energy.
    Why are IR and heat often interchanged?

    What? atoms *only* vibrate in a narrow range of frequencies and move at a narrow range of speeds equivalent to the IR band??

    Can someone explain the paradox?
     
  9. Nov 16, 2004 #8

    Integral

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Heat is a very well defined physical term in themodynamics which has nothing specific to say about infrared.

    Our body and brain, associate a sensation we call heat with the ifrared band of radiation. This meaning of heat is only "sort of" related to the physical meaning of the word.
     
  10. Nov 16, 2004 #9
    well water molecules vibrate at the same frequency as microwaves, which is why microwaves heat your food. from the inside out.

    now electrons when excited from their ground state absorb only a certain frequency, and when going back down, they give off that frequency, and that can be IR or ultra violet, depending of weather it jups from what orbital to what orbital
     
  11. Nov 17, 2004 #10

    krab

    User Avatar
    Science Advisor

    Kinetic energy is a useful concept for macroscopic objects; less useful for individual particles.

    For example, an oxygen molecule has 6 degrees of freedom: 3 translational, 2 rotational, 1 vibrational. Each of these can contain some of the thermal energy. The first 3 you would call "kinetic". Maybe the rotational ones too. The vibrational one is from a classical (non-QM) point of view trading between kinetic and potential energy at a rate of billions of cycles per second. It's not useful to talk about KE here; more useful to just consider that summed over a macroscopic number (10^23), the vibrational mode contains x amount of the thermal energy.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Is heat kinetic energy
  1. Kinetic energy (Replies: 4)

Loading...