The universal law of gravitation is an example of the laws of a natural mechanical system.

For example, the universal law of gravitation relative to a system of centers of gravity of the planets was designed to enable the astronomer to determine the position of any one of the planets at any moment of time, given the space-time coordinates of each component of the system and its mechanical properties at any other given moment of time. (PS 20)

This page was last updated on July 24, 1996, by Rob Sable.