Physical Science

A unit circle is an important part of trigonometry and can define right angle relationships known as sine, cosine and tangent.

By Nokware Knight & Austin Henderson

A multiplication table is an easy-to-use grid of numbers that can help you learn to multiply quickly by using the chart and, eventually, your memory.

By Kristen Hall-Geisler & Austin Henderson

Real numbers are the opposite of imaginary numbers and include every number you can think of.

By Jesslyn Shields & Yara Simón

We all have favorite colors. But have you ever considered why you like one color more than another?

By Allison Troutner

Discovered in the early 1800s from a chunk of smuggled platinum ore, rhodium is the most valuable precious metal on the planet today, used mainly for keeping car emissions in check.

By Allison Troutner & Austin Henderson

Numerators and denominators, oh my! It sounds complicated, but learning how to multiply fractions is easy. It just takes three simple steps.

By Jesslyn Shields

Finding the range of a set of numbers is an easy subtraction problem!

By Jesslyn Shields

Cadmium is a natural metal and the leading component in rechargeable batteries and solar cells. It is also highly toxic and heavily regulated.

By Allison Troutner

Dividing fractions is easy once you learn a couple of rules and remember three words — keep, change and flip.

By Jesslyn Shields

A perfect square is a number, but it can also be explained using an actual square.

By Jesslyn Shields & Austin Henderson

Without gasoline, the world as we know it would grind to a screeching halt. The U.S. alone consumes well over a hundred billion gallons of gasoline per year. Learn all about this vital fuel.

By Marshall Brain

You're driving down the road on a sunny day, and you see a puddle of water coming up. You look again and it's gone! What happened? You’ll be able to answer that question if you read our miraculous mirage article.

By Tom Harris

Have you seen investigators on crime shows who spray some stuff on a "clean" carpet and suddenly -- blood stains! Well, of all the fictional technology on TV, it turns out this stuff is real! Find out how luminol reveals the blood.

By Tom Harris

Magnets produce magnetic fields and attract metals like iron, nickel and cobalt. They're used in all sorts of applications but how are they made and how do they work?

By Tracy V. Wilson & Chris Pollette

What makes sound a weapon? Review the basics of sound and discover exactly how the LRAD produces its "beam of sound." We'll also explore LRAD's hailing and warning abilities and other uses for sound.

By Tracy V. Wilson

If water is made up of hydrogen and oxygen, why can't we breathe underwater? It has to do with how molecules combine and how the human lung functions.

Ever wondered exactly what they "artificial flavors" in your candy are, and why no specific ingredients are listed? Find out in this article.

By HowStuffWorks.com Contributors & Yara Simón

The idea that something so intangible as acoustic levitation can lift objects may seem unbelievable, but it's a real phenomenon.

By Tracy V. Wilson

When there's a suspect in a crime and the evidence includes a handwritten note, investigators may call in handwriting experts to see if there's a match. How exactly do experts go about analyzing someone's handwriting?

By Julia Layton

If serial killer Ted Bundy hadn't been a biter, he might never have been caught. What can bite marks and teeth tell us about a person?

By Shanna Freeman & Melanie Radzicki McManus

Forensic scientists can help law enforcement catch even the wiliest perpetrator. What are their techniques?

By Stephanie Watson

Will your favorite criminal drama feature investigators packing calculators instead of heat? Probably not. However, forensic accountants help investigate criminal and civil cases involving financial issues like fraud.

By Shanna Freeman

Detectives arrive at a crime scene and lift fingerprints from the murder weapon. They'll use these oily markings to catch their criminal. But how do they match the print to the killer?

By Stephanie Watson

If you were to touch dry ice, it wouldn't be anything like touching water ice. So what's it like? Is it hot or cold? And would it leave a mark?

By Marshall Brain & Austin Henderson

We've all been told not to put aluminum foil in the microwave. Stories of incredible explosions and fires are usually at the center of these ominous warnings. Why is that?

By Marshall Brain