# Newton's law of universal gravitation facts for kids

**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

In this equation:

*F*_{g}is the total gravitational force between the two objects.*G*is the gravitational constant.*m*_{1}is the mass of the first object.*m*_{2}is the mass of the second object.*r*is the distance between the centres of the objects.

In SI units, *F*_{g} is measured in newtons (N), *m*_{1} and *m*_{2} in kilograms (kg), *r* in metres (m), and the constant *G* is approximately equal to ×10^{−11} N m^{2} kg^{−2}. 6.674

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