Physical Science

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

When you watch crime drama on TV, you don't usually see what happens after the police and ambulance leave a murder scene. One thing those people do not do is clean up the blood. That's the work of a whole different team.

By Julia Layton

If the idea of being completely knocked out by a cocktail of drugs while doctors operate on you freaks you out, you're not the only one. But that's not what anesthesia is all about it — and it might scare you less if you understand how it works.

By Shanna Freeman & Nicole Antonio

When the power goes out and is later restored, how do you know what time to set your clocks to? Have you ever wondered how time is regulated? Learn how scientists determine exact time.

By Douglas Dwyer

About 90 percent of Americans consume some form of caffeine every day: It's our most popular drug by far. What's so special about this stimulant?

By Marshall Brain, Charles W. Bryant & Matt Cunningham

Helium balloons tend to fascinate adults and children alike (and it's not just the Donald Duck voice thing, though that is a big draw). Learn all about helium and why it floats!

By Marshall Brain

Nuclear radiation can be extremely beneficial or extremely harmful -- it all depends on how it's used. Learn what nuclear radiation is all about.

By Marshall Brain & Desiree Bowie

Whether the circle is as big as planet Mars or as small as a tennis ball, the ratio of its circumference divided by its diameter will always equal pi (3.14). But why?

By Marshall Brain, Dave Roos & Austin Henderson

Helium is the second lightest element on the Periodic Table. How is helium created?

By Patrick J. Kiger

You may know a bit about polygraphs, but do you know which physical reactions it actually monitors?

The decibel scale measures sound based on human hearing, which makes it one of the most unusual scientific measurements. How are decibel calculated and what do they tell us about sound?

By Sascha Bos

I recently used chlorine bleach to clean the siding on my house, and I was amazed at how well it worked! What is bleach? How does it remove stains? Is the chlorine in bleach the same as the chlorine in drinking water or in swimming pools? Is chlorine safe to use?

By Yara Simón

Just how far can the human eye see? There's no exact formula to figuring it out, but we do have an idea.

By Patrick J. Kiger

I once saw this device shaped like a light bulb. It had a vertical support inside it, and on that support there were four vanes with four diamonds on the end. One side of the diamond was black and the other was white. I did a little research and found out that it was called a Crookes' radiometer -- how does it work?

I have a thin piece of plastic mounted on the back window of my RV. It magnifies things so I can see better when I'm backing up. How can such a thin piece of plastic magnify things? A regular glass magnifying lens would have to be curved on both sides and much thicker.

By Austin Henderson

Bullet size is measured in calibers, but how are wires and nails measured? Learn about bullet size and caliber in this article.

Many ads for new clocks advertise their ability to automatically synchronize themselves with the atomic clock in Boulder, Colorado. This atomic clock is more precise because it uses the frequencies of atoms as its resonator.

Chemical formulas provide a concise explanation for reactions. In this article, we explain the formula for the reaction in a smoke detector.

When an airplane flies faster than the speed of sound, you hear a large booming sound. But how can something that seems so simple cause such a boom?

By Austin Henderson

Radar is used to track storms, planes, and weapons and also to create topographic maps. Learn about radar, radar technology and Doppler shift.

By Marshall Brain

A sound wave alone probably won't kill you. Crank the volume on a terrible song, though, and you just might annoy everyone to death.

By Oisin Curran

These small molecules are the foundation for much bigger things, from ordinary household products around us to essential components within our bodies.

By Debbie Swanson

Polymers are the basic components in so many of the products we use each day.

By Debbie Swanson

What if there are colors within the visible spectrum that our brains can't perceive? In fact, there are. They're called impossible colors. But some researchers think they've discovered a way to see the impossible.

By Dave Roos