  In this work we suggest a sufficiently simple for understanding "without
knowing the details of the quantum gravity" and quite correct deduction of the
Unruh temperature (but not whole Unruh radiation process!). Firstly, we shall
directly apply usual consequences of the Unruh radiation and temperature at
surface gravity of a large spherical physical system and we shall show that
corresponding thermal energy can be formally quite correctly presented as the
potential energy absolute value of the classical gravitational interaction
between this large and a small quantum system with well defined
characteristics. Secondly, we shall inversely "postulate" small quantum system
with necessary well defined characteristics and then, after "supposition" on
the equivalence between potential energy absolute value of its gravitational
interaction with large system with thermal energy, we shall obtain exact value
of the Unruh temperature. Moreover, by very simple and correct application of
suggested formalism (with small quantum system) at thermodynamic laws, we shall
successfully study other thermodynamic characteristics, especially entropy,
characteristic for Unruh and Hawking radiation
