The kinetic field theory (KFT), which does not contradict observations, conservation laws and equations of the general theory of relativity (GRT), was constructed. Objections of A. Poincaré and other scientists against a similar attempt by J. Lesage (1784) were eliminated by assuming that the background particles responsible for the transmission of gravitational, inertial, electric, magnetic, electromagnetic and some other types of information have a strongly elongated needle-shaped (interobraznyi) form. Among possible applications of KFT are the use of background particles as an inexhaustible and environmentally friendly source of energy, control of tectonic processes in order to provide people and pets with safety during earthquakes, and many others.

Solving problems related to the study of kinematics, dynamics, and energy of free, non-flooded liquid jets is fraught with a number of specific difficulties. These jets differ from many other types of motion of a continuous medium by the presence of a free surface, the shape of which changes over time according to some unknown law.

To predict the places of greatest wear on the walls of the ore intake, to find the kinetic energy of falling pieces of ore, the possible degree of crushing of the material during bypass, and to solve some other issues, it is necessary to know the kinematics of the movement of a single piece of ore in the ore intake.

Practice shows that in ore mines, where for stripping of useful minerals are used mass explosions, the maintenance of mine workings causes significant difficulties, which with increasing depth of development increases.

An unsteady axisymmetric unspun flow of incompressible ideal fluid in the absence of mass forces is considered. The problem is solved in a cylindrical coordinate system (g, f , z), the origin of which coincides with the center of a circular outlet hole of very large diameter, the z-axis with the axis of symmetry of the flow, the position of the plane f = 0 is indifferent due to the axial symmetry.

At the end of XIX century researchers pointed out the internal instability of a free jet caused by capillary forces applied to its surface.