An important problem of the change in the effective parameters of averaged motions in nonlinear systems is described. This problem is known in physics for a long time. It is concerned with the derivation of bodies motion equations taking into account the collisions with the molecules of the surrounding gas. Many researchers believe implicitly that this problem is essential only for the transfer from microscopic equations to macroscopic ones. However this problem reveals often itself in the present-day macroscopic physics.
