Further ExplorationNewton's Law of Universal Gravitation
T. Henderson, The Physics Classroom - An excellent tutorial on Newton's theory of gravity including practice exercises.Newton and Einstein
J. Imamura, U. Oregon - A summary of Newton's laws, their shortcomings and Einstein's theories of gravity.Inverse Square Law
R. Nave, Hyperphysics - A detailed look at inverse square relationships throughout physics.
ClassicsPhilosophiae Naturalis Principia Mathematica
I. Newton - A reproduction of the preface to Newton's famed Principia (1687) and links to the full text.Philosophiae Principia
A photograph of Newton's own copy of the Principia and the fabled apple tree.
News & EventsCavendish Experiment in Top Ten of All Time
The Cavendish Experiment was selected by physicists as one of the ten most beautiful experiments of all time.Gravitational Constant Controversy
The story of the controversy over the value of the gravitational constant.Measuring the Gravitational Constant
An article from Physics Today about a modern-day experiment to measure the gravitational constant.Current Science News
News from around the world of science.
ResearchBig G Measurement
University of Washington Physicists determining the value of the gravitational constant.Measuring Gravity on Small Length Scales
This Stanford University research group is measuring the force of gravity on very small length scales and testing Newton's and Einstein's models of gravitation.Google Scholar
Google - Research database allows searching of the scholarly literature.
B. Willis, Worsley School - A simulation of the effect of gravity on orbiting bodies. Illustrates Kepler's laws on which Newton based his theories.The Cavendish Experiment
U. Kruse & T. Tran, U. Saskatchewan - A detailed explanation of the Cavendish Experiment, including a simulation and pictures of the real apparatus.Newtonian Orbit Simulator
Explore the concept of orbits as Newton envisioned them with this Java simulation of Newton's original thought experiment.