The space between two large horizontal plates if filled with helium. The plate separation equal `l = 50 mm`. The lower plates is kept at a temperature `T_1 = 290 K`, the upper, at `T_2 = 330 K`. Find the heat flow density if the gas pressure is close to standard.

Explanation

`k = (1)/(3) sqrt((8 RT)/(pi M)) (1)/(sqrt(2) pi d^2 n) mn (R(i)/(2))/(M) = (R^(3//2) i T^(3//2))/(3 pi^(3//2) d^2 sqrt(M) N_A)`
Then from the previous problem
`q = (2 i R^(3//2) (T_2^(3//2) - T_1^(3//2)))/(9 pi^(3//2) d^2 sqrt(M) N_A l), i = 3 here`.