Let ๐_{๐ธ} be the mass of the Earth and *m *be the mass of an object on its surface. If R is the radius of the Earth, then according to the universal law of gravitation, the gravitational force (F) acting between the Earth and the object is given by the relation:

๐น = {๐บ๐_๐ธ๐ \over ๐ ^2}