Georgia State University
Georgia State University: Hyper Physics: Air Friction
Physics lab definition of air fiction. Part of a hypertext physics course on sound.
NASA
Nasa: Beginner's Guide to Aerodynamics
Includes exhaustive information and a wealth of activities pertaining to aerodynamics and the physics of flight.
Exploratorium
Exploratorium: The Science of Sports Cycling
A detailed look at the aerodynamic principles associated with cycling. Good science and even better web page design. Includes an online calculator that allows the user to calculate the aerodynamic drag and propulsive power of a bicyclist...
NASA
Nasa: Beginner's Guide to Aerodynamics
This site from NASA uses a colorful graphic to illustrate why objects reach terminal velocity. Provides equation for the terminal velocity of an object. Graphic is accompanied by a simple explanation.