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Homework Help: Maxwel distribution

  1. Nov 29, 2008 #1
    1. The problem statement, all variables and given/known data
    A gas consisting of 15,200 molecules, each of mass 2.00×10^−26 kg , has the following distribution of speeds, which crudely mimics the Maxwell distribution:
    Number of Molecules
    1600
    4100
    4700
    3100
    1300
    400
    Speed
    210
    420
    630
    840
    1050
    1260

    Determine Vrms for this distribution of speeds.
    Given your value for Vrms , what (effective) temperature would you assign to this gas?

    2. Relevant equations

    Vrms = square root {Average V^2} or square root {3kT/m}

    3. The attempt at a solution

    So I squared all the values and then divided by the total number to obrain (Average velocity^2) and then took the square root ...the attempt failed..many thanks to anyone who helps!
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Nov 29, 2008 #2

    Doc Al

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    Staff: Mentor

    You need to first find the weighted average of the squares of the speeds.
     
  4. Nov 29, 2008 #3

    malawi_glenn

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    Science Advisor
    Homework Helper

    what do you mean by "squaring all values"?

    Do you weight all speed^2 with their occurence?
     
  5. Nov 29, 2008 #4
    so the average of the squares of the speeds was 6.6885*10^5
     
  6. Nov 29, 2008 #5

    sorry for the confusion...i meant squaring all speeds..

    and I dont know wht you mean by your second question :S
     
  7. Nov 29, 2008 #6

    malawi_glenn

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    then you did not do the weigted average.. look it up
     
  8. Nov 30, 2008 #7
    square root { (3kT) /m}

    is that the weighted average?
     
  9. Nov 30, 2008 #8

    malawi_glenn

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