On Relativistic Generalization of Gravitational Force

The problem of point particle in the 1/r gravitational field was studied in SR-based Mechanics. Equations of motion under assumption of field dependent proper mass were obtained in the relativistic Lagrangean framework. The dependence of proper mass on field strength was derived from the equations of particle motion. The result was the elimination of 1/r divergence. It was shown that a photon in a gravitational field may be described in terms of a refracting massless medium. This makes the gravity phenomenon compatible with SR. New results concerning gravitational properties of particle and photon are discussed. The conclusion is made that the approach of field-dependent proper mass is perspective for further studies on divergence-free gravitational field development. Key words: Relativity, gravity, particle, photon, speed of light, proper mass variation. {\small\it PACS 03.30.+p, 04.20.-g}