Grades 9-12. Describes the logic behind the development of Newton's law of universal gravitation. Beginning with Johannes Kepler and his three laws of planetary motion, content walks the reader through Newton's thought process and development of this theory. Detailed diagrams and animation of planetary motion are also provided.

In this site from the physics classroom, kinetic energy is defined and discussed. The equation for its computation is also given and practice computation problems are given.

This tutorial looks at the behavior of sound waves, specifically focusing upon sound interference and beats. Learn more about it and then take a short quiz to check your understanding.

From The Physics Classroom. Uses easy- to-understand language to discuss how circular motion principles apply to the motion of satellites. Describes the tangential velocity and centripetal acceleration of a satellite. Includes many diagrams and a Check Your Understanding section.

This high school physics lesson focuses on the application of the Doppler effect to sound. Discusses what the Doppler effect is, offers examples of its occurrence, and explains what shock waves and sonic boom are.

A tutorial on the electromagnetic and visible spectra. Discusses dispersion and how perceptions of white and black are related to the visible light spectrum.

A demonstration involving an elephant and a feather and explanation of why all objects maintain the same acceleration in the state of free fall without any air resistance.

This lesson in high school physics on Newton's Second Law of Motion provides a discussion of free fall and air resistance, and answers, "Why do objects which encounter air resistance ultimately reach a terminal velocity?" and "In situations in which there is air resistance, why do more massive objects fall faster than less massive objects?"

This is part of a lesson on Newton's Laws of Motion that focuses on inertia and mass. It restates Newton's first law of motion. The lesson also gives a helpful visual description concerning friction.

The three laws of planetary motion as described by Kepler are stated and elaborated upon. Useful graphics and an easy-to-understand language are used to explain the nature of planetary motion. Both conceptual and mathematical. Includes a Check Your Understanding section.

This excellent high school physics tutorial from The Physics Classroom investigates motion formulas using several problem-solving strategies including diagrams, equations, and lists.

This tutorial explains light absorption, reflection and transmission in a clear and concise manner. Provides a "Check Your Understanding" section as well as additional links on color and light.

The mathematics associated with the motion of satellites is described. Equations (for period, velocity, acceleration and force) are stated, symbols described, and sample problems solved. Includes five practice problems with solutions and answers. Excellent graphics.

A very good introduction to the world of waves. Waves and wavelike motion, what is a wave, and categories of waves are the topics examined in this site. Many links to other wave sites.

States the equation of Newton's law of universal gravitation. States the value of G and uses the equation to solve problems.

In this thorough lesson, nodes and antinodes are explained and compared to crests and troughs. A "Check Your Understanding," set of questions is included at the end of the lesson with answers.

Topics covered include what acceleration is, the difference between constant and non-constant acceleration, acceleration in a free-falling object, the equation used to compute acceleration, and the difference between positive and negative acceleration. Also includes some practice problems.

A GIF animation comparing the motion of three cars. A graphical depiction is given. Includes three thoughtful questions with answers in a pop-up menu.

A lesson on free fall covers the fact that free-falling objects do not encounter air resistance and all free-falling objects (on Earth) accelerate downwards at a rate of approximately 10 m/s/s (to be exact, 9.8 m/s/s).