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Homework Help: Need help Entropy

  1. Nov 30, 2007 #1
    Need help....Entropy

    The interatomic spring stiffness for magnesium is determined from Young's modulus measurements to be 12 N/m. The mass of one mole of magnesium is 0.012 kg. If we model a block of magnesium as a collection of atomic "oscillators" (masses on springs), what is one quantum of energy for one of these atomic oscillators? Note that since each oscillator is attached to two "springs", and each "spring" is half the length of the interatomic bond, the effective interatomic spring stiffness for one of these oscillators is 4 times the calculated value given above.

    Use these precise values for the constants:
    h= 1.0546*10^-34 J · s (Planck's constant divided by 2)
    Avogadro's number = 6.02211023 molecules/mole
    k = 1.3807*10^-23 J/K (the Boltzmann constant)

    one quantum =

    i thought you would use

    hw = h*sqrt(ks/m) = (1.05E-34)*sqrt((4*12 N/M)/(0.012 kg) = 6.64e-33

    but its not...could someone tell me what I'm doing wrong? Thanks!
  2. jcsd
  3. Apr 17, 2008 #2
    Is that the wrong equation to use for this problem? I also tried that equation and got an incorrect answer for a similar problem with different values.
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