Analysis of a number of macroscopic models in which an infinitely thin boundary is laid showed that the force arising at the boundary is determined, naturally, by the gradient of the macroscopic potential, and not by its microscopic gradients. The calculation of the form of the distribution of the gravitational potential near the boundary determined by the position of the accelerated object allowed us to obtain, as a first approximation, the ratio of the gravitational and inertial masses, which depends on the acceleration and the acceleration time of the object as it approaches its speed to the speed of light.