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Homework Help: No clue

  1. Jan 23, 2005 #1
    i dont know how to do this...nothing comes to mind. any help will be appreciated!

    A pressure as low as 4×10-11Pa has been obtained. Suppose a chamber contains helium at this pressure and at temperature 380K. Estimate the collision time (tau) for helium in the chamber. Take the diameter of a helium molecule to be 1×10-10m.
  2. jcsd
  3. Jan 23, 2005 #2


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    Do u know the formula giving the mean free path ([itex] \lambda [/itex])??If so,combine it with the thermal velocity to find the mean collision time...

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