For masses m and M that are separated by a distance r, the gravitation
force of one mass on the other is:
G is the universal gravitational constant that measures the "strength" of the gravitational interaction: G = 6.67 x 10-11 N m2 / kg2
For an object of mass m on the Earth's surface, the gravitational force is:
|≡ - m g|
This formula defines the gravitational acceleration g.