<P> η 0 = 1 3 v _̄ C m l (\ displaystyle \ quad \ eta _ (0) = (\ frac (1) (3)) (\ bar (v)) Cml) </P> <P> Combining this equation with the equation for mean free path gives </P> <P> η 0 = 1 3 2 m ⋅ v _̄ σ (\ displaystyle \ quad \ eta _ (0) = (\ frac (1) (3 (\ sqrt (2)))) (\ frac (m \ cdot (\ bar (v))) (\ sigma))) </P> <P> From statistical thermodynamics for gases we have equations relating average molecular speed to most likely speed and further to temperature . These statistical results gives the average (equilibrium) molecular speed as </P>

Write a short note on atomic size from kinetic theory of gases perspective