Abstract: Four kinds of effusion problems in thermal physics is calculated in detail and the results are discussed.The problems for constant temperature effusion have analytlcal solutions,but the adiabatic effusion problems often have only numerical results due to limited mathematics knowledge.The conditions of quasi-equilibrium state in effusion process are also analyzed generally.They will help teachers and students get entire understanding of the effusion problems.

Key words: effusion, constant temperature container, adiabatic container, density of molecular number, equilibrium state