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Homework Help: 4k helium wave packet model

  1. Sep 10, 2015 #1
    1. The problem statement, all variables and given/known data
    can liquid helium at 4k (.1 nanometers interatomic spacing) be modeled by non spreading wave packets?

    2. Relevant equations

    W(k) was Taylor expanded to a quadratic term Δpx2/(2mħ)

    The book then sas for a non expanding wave packet:

    |t| << mħ/Δpx2

    Another relation:

    |t| Δvx =|t| Δpx/m << ħ/Δpx = Δx

    3. The attempt at a solution
    I'm not sure where to begin. I figure... Δx is 1×10^-10 meters

    Then I could say

    |t| << mΔx2

    Which tell me t must be very small since we are talking about ≈ (10^-10)^2

    Other then that I don't know where to go from here.
  2. jcsd
  3. Sep 15, 2015 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
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