Newton's law of universal gravitation

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
formula_1
In this equation:
In SI units, is measured in newtons (N), and in kilograms (kg), in metres (m), and the constant is approximately equal to .