The Formulas for Calculating Surface Gravity and Rotational period of celestial Body and Black Hole in the A xial Spherical-Space

This paper reports aformulafor calculating the average gravity on the surface ofrotationalobjectderived from Hoffman-Wellenhof'sdefinitionand modern physics.This formula shows that there is a constant physical and mathematical relationship among the (average) surface gravity, (average) rotational period, total mass and (average) radius for a celestial body that rotates around its axis. Subsequently, two additional formulas emerge: one for determining the average rotational period of celestial bodies such as planets in the Solar system, stars and neutron stars in the Milky Way system; and another for calculating the rotational period of a black hole. These three formulas are characterized by their simplicity, precision and reliability. Furthermore, the theory of motion principle of celestial body in the axial spherical-space is a complement for universal gravitation and relativityto explain the nature of spin, magnetic field and light.