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Homework Help: Kinetic energy of neutron

  1. Sep 24, 2010 #1
    1. The problem statement, all variables and given/known data

    Suppose you want to observe neutron diffraction in a crystal with 0.27nm spacing between lattice planes.

    Part A asks for the momentum of neutrons with a wavelength equal to the spacing. I used p = h/lambda to get the correct answer 2.5×10−24kgms-1

    Question1:

    Find the kinetic energy of neutrons having wavelength equal to this spacing.

    Question2:
    If these neutrons constituted an ideal gas, what would be the gas temperature?
    2. Relevant equations

    Q1. k=0.5mv2
    Q2. PV=nRT
    3. The attempt at a solution
    Q1: I've tried a couple of different methods, dunno if i'm going the right way with this.
    k=0.5mv2
    0.5(1.67*10^-27)(1.47*10^3)^2 = 1.80*10^-21J

    is this correct?
    Q2: I have no idea.
    Thanks in advance.
     
    Last edited: Sep 24, 2010
  2. jcsd
  3. Sep 24, 2010 #2

    ehild

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    Homework Helper

    Q1 is correct.

    What is the average kinetic energy of an atom or molecule in an ideal gas?

    ehild
     
  4. Sep 24, 2010 #3
    Ah, cool.

    so 0.5mv^2 = (3/2)kT? So just rearrange to get T with k being boltzmann's constant?

    Helpful as always ehild. Thanks.
     
  5. Sep 25, 2010 #4

    ehild

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    Homework Helper

    I hope it is that easy. Try.


    ehild
     
  6. Sep 26, 2010 #5
    correct, thanks
     
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