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Speed of Hydrogen / oxygen

  1. Nov 30, 2007 #1

    ssb

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    1. The problem statement, all variables and given/known data

    Lets say at room temp an atom of hydrogen moves at 3000 m/s. Lets say all things the same except you replace the hydrogen with oxygen. The oxygen is about 16 times the molar mass than hydrogen. Does this mean that the oxygen will travel at (1/16)*3000 m/s?




    3. The attempt at a solution

    This is not really a homework question but we are dealing with stuff like this in class and it has been confusing me. 1/16 times the original velocity is my guess.
     
  2. jcsd
  3. Nov 30, 2007 #2

    Dick

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    That's a wrong guess. It's the kinetic energy of the molecules that remains the same.
     
  4. Nov 30, 2007 #3

    ssb

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    well then if thats the case then the velocity would stay the same... right?
     
  5. Nov 30, 2007 #4

    Dick

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    Nooooo! KE=(1/2)*m*v^2. So mH*vH^2=mO*vO^2. If mO=16*mH, how are vH and vO related?
     
  6. Nov 30, 2007 #5

    ssb

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    this would make

    sqrt(1/16*vH^2) = sqrt(vO^2)

    so vO would = 1/4 vH

    so if H was moving at 3000 m/s then O would be moving at 750 m/s.
     
  7. Nov 30, 2007 #6

    Dick

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    That's much better.
     
  8. Nov 30, 2007 #7

    ssb

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    heheheh thankyou very much
     
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