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Homework Help: Vrms of Helium

  1. Nov 19, 2008 #1
    1. The problem statement, all variables and given/known data

    What is the root mean square speed of Helium at 5K?

    2. Relevant equations


    3. The attempt at a solution

    I plugged all the numbers in and keep getting 7.19*10-12. The computer keeps telling me that it is not correct. The next question ask for the avg KE which I found to be 1.04×10−22. I tried using 2/3 Kavg/kb and got 7.21*10-12. The computer tells me that is wrong also. Where am I messing up?
  2. jcsd
  3. Nov 19, 2008 #2


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    Staff Emeritus
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    Homework Helper

    Did you check the units on kB, T, and m? What values did you use for them?
  4. Nov 19, 2008 #3
    That is the whole proble. I remember overhearing the professor and another student talking about converting amu to kg. I plugged in the conversion and got the answer. It has been a long week and day. Guess my brain is still fried from the calculus test tonight. Thanks for the help.
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