Tuesday, July 13, 2010

The "Sweet Spot" of a Baseball Bat

The sweet spot of a baseball bat is the point at which it feels the best to hit the ball. You know what I'm talking about. There's no excess vibrations traveling from the bat to your hands, and the ball soars out of the park. The sweet spot has a scientific term: the center of percussion.

Every time you hit a baseball bat with a ball, vibrations emanate along the bat in every direction from where it was hit. This is what causes your hands to vibrate when you hit the ball too low or too high on the bat. The center of percussion is the point where all the vibrations in the bat cancel each other out.

This video from the Exploratorium goes into some of the physics behind hitting a baseball, and concludes with a musical application of the center of percussion.

Tuesday, July 6, 2010

Diffracted Fireworks

From Around DC

Last Sunday, I settled on the grass next to the Washington Monument to watch the Fourth of July fireworks, armed with a pair of diffraction glasses. Diffraction glasses, sometimes called rainbow glasses, have a special plastic lens which splits white light into the whole visible spectrum. Each lens has thousands of microscopic slits that cause the lens to act like a prism when light hits them. The colors in the rainbow you see are even in the order you learned in kindergarten with ROY G BIV--red, orange, yellow, green, blue, indigo, violet. This is the exact same process that happens when you see rainbows after a storm. In the case of rainbows in the wild, white light from the sun gets diffracted through the raindrops in the air. The rainbow that you see through diffraction glasses is called a spectrum.

Because white light contains all the colors of the rainbow, you see all the colors when it gets diffracted. Everyday lights, even colored ones, shine in more than one single color, even if it seems like one color to you. If you look at a blue light through diffraction glasses you only see the colors that make up that particular blue--usually green, blue, and indigo. The other colors of the spectrum will be absent. The same thing will happen if you look at an orange light. You will only see red, orange, and yellow in the diffraction glasses.

Lasers are a special type of light that only emit in one color. If you look at the light from a laser using diffraction glasses, you will only see a single dot in the laser's spectrum, the same color as the laser.

Here's a few more pictures of diffracted fireworks.

From Around DC
From Around DC
From Around DC

Friday, July 2, 2010

Science in Music

When science and music combine, a beautiful thing happens. Take a look at these videos, and maybe these songs will teach you a little something about the way the universe works.

The Large Hadron Collider (LHC) at the CERN lab over in Europe was finished recently, and physicists think that it will help answer questions about things we don't currently understand in particle physics. What the LHC does (and particle accelerators in general) is get particles, often protons, moving at extremely high speeds with lots of energy. Then they smash them into each other. The protons break apart into a shower of other particles. Physicists examine these other particles to try to determine what the universe is made of.

Learn more specifics of the LHC via rap!

And with this video you can watch They Might Be Giants teach us about the Sun.

For more calculus-based fun, check out the Gauss's Law Song. Gauss's Law is a law describing how electric charge is related to electric field. In the Gauss's Law Song, physics professor Walter F. Smith explains how to do some of the math behind the law. Many more physics songs can be found at his website.

Lastly, this cute little cartoon tells us the seven things necessary for something to be alive.