Newton's universal law of gravitation is a physical law that describes the attraction between two objects with mass. It is talked about in Isaac Newton's Philosophiae Naturalis Principia Mathematica. The law is part of classical mechanics.

The formula is

NewtonsLawOfUniversalGravitation.svg

In this equation:

  • Fg is the total gravitational force between the two objects.
  • G is the gravitational constant.
  • m1 is the mass of the first object.
  • m2 is the mass of the second object.
  • r is the distance between the centers of the objects.

In SI units, Fg is measured in newtons (N), m1 and m2 in kilograms (kg), r in metres (m), and the constant G is approximately equal to 6.674×10−11 N m2 kg−2.