[zeshkani]

ok today in lecture the prof calculated the mean free path og N2 at 1atm and 25C  and got 70nm
but when i tired to do that i get a total different answer

lambda= (kT)/sigma*P*2^1/2
i believe k is boltzmann constant

so with all the numbers in
lambda= (1.38065e^-23*298.15K)/ (.43nm^2)*1*2^1/2
         =  6.7692e^-21  and thats no way the right answer
so my question is em i doing this calculation wrong, or there is something more too it

[Yggdrasil]

Always include units in your calculation.

[zeshkani]

i figured it out, is was just using p in atm but it needs to be in Pa and the cross section was .52 which i also used like that but this was wrong, its (.52e^-2)^2m
its so easy know, next time i wont just start a new topic, it just took me some time to figure it out