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Homework Help: Fundemental Frequency units?

  1. May 13, 2009 #1
    1. The problem statement, all variables and given/known data
    The fundamental vibrational frequency of gaseous 14N16O is 1904 cm-1.

    a. Calculate the force constant, using the simple harmonic oscillator model

    2. Relevant equations

    K=u((2pi)(v))^2 u=reduced mass

    3. The attempt at a solution

    u=[(14)(16)/(30)] (1kg/6.02e^26)= 1.24e^-26 Kg/molecules

    K=(1.24e^-26 kg)((2pi)(1904 cm^-1))^2= 1.77e^-22 kg m^2

    How do I get the answer in N/m ??
  2. jcsd
  3. May 13, 2009 #2


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    What does it mean when there is a frequency given in cm-1? Frequency should be given in Hz (or per time of some sort). Perhaps instead of "fundamental frequency" they meant "wave number/vector"?
  4. May 13, 2009 #3
    cm^-1 is the wavenumber.
  5. May 13, 2009 #4


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    If you have K = u(2pi*v) why are you plugging in your wave number for v? v is a frequency yes? So how do you convert a wave number into frequency?
  6. May 14, 2009 #5

    Good point, I will change wave number to frequency.
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