AC / DC: What's the Difference?

This animated essay from the American Experience Web site explains the difference between alternating and direct electric current and offers in-depth explanations about the role played by a battery, light bulb, wire, and generator.

Aerodynamics: What Causes Lift?

How does an airplane stay aloft when upside down? This media-rich essay from the NOVA Web site offers an explanation based on Newton's third law of motion.

Atoms: The Space Between

This video segment adapted from A Science Odyssey takes a look at the scale of the atom and the tremendous amount of space between the electrons and the nucleus. If all this empty space exists in matter, how can any substance be solid?

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The Beginnings of the Telescope

This animated essay from the NOVA Web site examines the design of Galileo's refracting telescope and Sir Isaac Newton's reflecting telescope.

Chernobyl: What Really Happened?

This text excerpted from Richard Rhodes' book, Nuclear Renewal and reprinted on the FRONTLINE Web site examines the causes of the Chernobyl accident.

Circular Motion

In this interactive activity featuring videos adapted from the Rutgers PAER Group, observe examples of circular motion. Can you find a common reason why the objects and people presented move in a circle?

Diamonds: The Science Behind the Sparkle

This illustrated essay from the NOVA Web site explains why the atomic structure of a diamond slows down light and produces a sparkle more brilliant than from any other colorless substance.

Einstein: How Smart Was He?

This essay from the NOVA Web site explores the impact Einstein made on physics and most everything we know about the cosmos.

Einstein's Special Theory of Relativity

What happens when you approach the speed of light? This video segment adapted from NOVA follows one of Albert Einstein's thought experiments and his quest to find the answer.

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Energy Transfer in a Trebuchet

On NOVA, a team of carpenters, timber framers, engineers, and historians recreate a medieval throwing machine called a trebuchet. This adapted video segment explores how understanding energy transfer informs their design.

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Everyday Radiation

How much radiation are we exposed to every day? Find out in this video segment adapted from FRONTLINE.

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FAQs About Nuclear Power

Nuclear physicist, Dr. Charles Till, answers questions about nuclear power in this interview from the FRONTLINE Web site.

Free-Falling and "Weightlessness"

Discover the difference between free-falling and weightlessness in this interactive activity from the NOVA Web site.

Fusion Energy Advances

In this report from the NewsHour, correspondent Spencer Michels reports on ongoing efforts to produce fusion energy to help fuel American energy independence.

Galileo: His Experiments

This interactive activity from the NOVA Web site samples Galileo's experiments with falling objects, projectiles, inclined planes, and pendulums.

Galileo on the Moon

Watch Apollo 15 astronaut David Scott perform Galileo's falling objects experiment on the Moon in this video segment from NASA.

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Galileo's Inclined Plane

How did Galileo figure out the mathematics of falling bodies? This video segment adapted from NOVA examines Galileo's work on motion.

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Galileo's Telescope

The invention of the telescope helped change our understanding of the universe. This video segment adapted from NOVA looks at Galileo's contribution to this technology.

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Galileo's Thought Experiment

How can Earth move through space without our feeling its motion? This video segment adapted from NOVA answers this question by dramatizing one of Galileo's thought experiments.

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Galileo: Timeline of His Life

This illustrated timeline from the NOVA Web site turns back the clock to the late 1500's to relive the dramatic life of one of the world's most renowned scientists.