Archimedes, the Center of Gravity, and the First Law of Mechanics

Book excerpt: Archimedes, the Center of Gravity, and the First Law of Mechanics deals with the most fundamental aspects of physics. The book describes the main events in the life of Archimedes and the content of his works. It goes on to discuss a large number of experiments relating to the equilibrium of suspended bodies under the influence of Earth's gravitational force. All experiments are clearly described and performed with simple, inexpensive materials. These experiments lead to a clear conceptual definition of the center of gravity of material bodies and illustrate practical procedures for locating it precisely. The conditions of stable, neutral, and unstable equilibrium are analyzed. Many equilibrium toys and games are described and explained. Historical aspects of the concept are presented, together with the theoretical values of center of gravity obtained by Archimedes. The book also explains how to build and calibrate precise balances and levers. Several experiments are performed leading to a mathematical definition of the center of gravity and the first law of mechanics, also called the law of the lever. Consequences of this law and different explanations of it are described at the end of the book, together with an exhaustive analysis of the works of Euclid and Archimedes.