Gravitational Force

We are all familiar with the force of gravity. It is a fundamental observed property of our universe that any two masses and experience an attracting force given by the formula

where is the distance between the centroids of the masses and at time , and is the gravitation constant.^B.2

The law of gravitation Eq.(B.2) can be accepted as an experimental fact which defines the concept of a force.^B.3 The giant conceptual leap taken by Newton was that the law of gravitation is universal--applying to celestial bodies as well as objects on earth. When a mass is ``dropped'' and allowed to ``fall'' in a gravitational field, it is observed to experience a uniform acceleration proportional to its mass. Newton's second law of motion (§B.1) quantifies this result.

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About the Author: Julius Orion Smith III
Julius Smith's background is in electrical engineering (BS Rice 1975, PhD Stanford 1983). He is presently Professor of Music and Associate Professor (by courtesy) of Electrical Engineering at Stanford's Center for Computer Research in Music and Acoustics (CCRMA), teaching courses and pursuing research related to signal processing applied to music and audio systems. See http://ccrma.stanford.edu/~jos/ for details.