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Q & A: mean free path detail

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Most recent answer: 01/13/2019
Q:
hello,my question is regarding the calculation of the mean free path that is used in ideal gas and other places.in the calculation there is a factor of 1/sqeuroot(2) that is added because the molecules are moving and speed is calculated as the average magnitude of the relative velocity. why does the relative velocity solves the problem of the molecules movement?thanks meny
- meny (age 24)
LA, CA, US
A:

The unofrm motion continues until a collision with another molecule occurs. The time until a collision depends only on the relative motion of the two molecules. The distance traveled in the lab frame in that time depends, however, on the speed of a single molecule in the lab frame, not the relative velocity of two molecules. 

Mike W.


(published on 01/13/2019)

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