Science Struck
Science Struck: What Is Gravity and How Does It Work
A very detailed look at gravitational force and the many theories that have been put forward to try to explain it. Includes lots of illustrations.
Khan Academy
Khan Academy: The Buoyant Force Does Not Get Smaller as You Sink
This article explains the buoyant force using a submarine as an example. It also discusses what determines the size of the buoyant force using a formula, and explains decompression sickness better known as the bends.
Georgia Department of Education
Ga Virtual Learning: Physical Science: Force and Motion
In this student-paced module, students apply Newton's Laws of Motion to everyday life, calculate mathematical relationships involving force and motion using algebraic formulas, and understand the difference between mass and weight.
Science Struck
Science Struck: A Comprehensive List of All the Physics Formulas
Provides a long list of physics formulas for easy reference.
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.
BBC
Bbc: Gcse Bitesize: Mass, Weight and Gravitational Field Strength
This lesson focuses on gravitational fields and includes what one is, the formula for gravity force, defining weight, formula for mass, an example of how to calculate gravity force, a practice question, and a link to a test.
NASA
Nasa Star Child: Planet Hop
Figure out your age and your weight on all the planets in the solar system using the formulas given here. Then type them into the correct place, and let the computer check to see if you are correct.