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Finding energy from Inertia and RPM

  1. Aug 5, 2013 #1
    Hello,

    I'm working on a generalized model for motor / gear systems in SPICE and came across something I don't understand:

    Given that the inertia, J, is in kg m^2
    and my base unit for angular velocity, w, is kRPM
    and the basic equation for energy is E = 1/2 J * w^2

    How or what is the conversion factor such that I get joules as my unit of energy?

    I feel really silly on this one, I can only claim memory loss...

    Thanks in advance,

    Mike
     
  2. jcsd
  3. Aug 5, 2013 #2

    SteamKing

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    If you convert RPM to radians/second, it's a done deal. 1 RPM = 2*pi radians/min. = 2*pi/60 rad/s

    1 joule = 1 N-m = 1 kg-m^2/s^2
     
  4. Aug 5, 2013 #3
    To be certain, let me read back what I think I understand -

    To get energy, I convert my angular velocity to radians per second and use this as omega in:

    E=1/2 omega^2 J

    Correct?
     
  5. Aug 5, 2013 #4

    SteamKing

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