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

Why T for Kinetic energy?

  1. Jul 27, 2008 #1
    For Kinetic energy, some books use K, and some T. Example:

    example: http://www.damtp.cam.ac.uk/user/tong/dynamics/clas.pdf

    in this text the Lagrangian is written: L = T - V

    V is used for potential energy and my guess why for that is because it is also used for potential in electromagnetism (voltage), but I can't imagine why T would be used instead of K.

    Just curious if somebody knows why?
  2. jcsd
  3. Jul 27, 2008 #2
    I've also seen U used for potential energy, and it's not uncommon for adjacent letters to be used for related quantities. That doesnt really answer your question though, but there are other things like charge (q) and current (i) that aren't really intuitive either.
  4. Jul 27, 2008 #3
    Some of the older books I have looked at (such as Introduction to Quantum Mechanics by Pauling, Wilson) have used T for the kinetic energy and K for the rotational quantum number. In others I have seen J used for the rotational quantum number and that can free up K for the kinetic energy...I have no idea if this is the actual reason for the change though (I have also seen some books use KE for the kinetic energy to avoid confusion or perhaps to add to it).
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook