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Homework Help: Temperature required for new rms speed

  1. Dec 4, 2011 #1
    1. The problem statement, all variables and given/known data
    c) Find T, the temperature at which He gas molecules have an rms speed of v = 733 m/s.


    2. Relevant equations
    Vrms = √(3kT/m)


    3. The attempt at a solution
    (Vrms2m)/3k = T
    (7332*.004kg)/(3*1.381e-23J/k) = T
    5.187e25k = T

    Any help with figuring out what I did wrong is appreciated!
     
  2. jcsd
  3. Dec 4, 2011 #2
    Is not 'm' the mass of one MOELECULE of hydrogen?
     
  4. Dec 4, 2011 #3
    You could use the following to solve if you are given the quantity of material (n):

    P*V=n*R*T <=> T=(P*V)/(n*R)

    For R is a constant: R=8.31
     
  5. Dec 4, 2011 #4
    Thank you grzz and mtayab1994 for responding. It would be easier if the problem did provide n to use PV = nRT. I am confused, should I be using .008 kg for the mass because helium gas has 2 atoms?
     
  6. Dec 4, 2011 #5
    no you are fine with using .004kg
     
    Last edited: Dec 4, 2011
  7. Dec 4, 2011 #6
    By the way you can use the following as well
    ee2357aaf50f4db86dac6622e7f8cc02.png
     
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