Physics4kids
Physics 4 Kids: Work Quiz
Take this ten question multiple choice quiz on the physics of work.
TeachEngineering
Teach Engineering: Solar System!
An introduction to our solar system: the planets, our Sun and our Moon. Students begin by learning the history and engineering of space travel. They make simple rockets to acquire a basic understanding Newton's third law of motion. They...
Other
Wikibooks: Physics Study Guide
A handy resource that gives an overview of equations and definitions pertinent to an introductory, college-level physics course, with two of its three sections focusing on motion-related topics and principles.
Wikimedia
Wikipedia: Centripetal Force
Wikipedia's site on centripetal force provides a section explaining the difference between centripetal force and centrifugal force. Includes formulas and hyperlinked terms.