Sunday, July 25, 2010

Cackling Cup - Sound Experiment

For this sound experiment, which we found in several different children's science books, but most recently in Awesome Experiments in Light and Sound, by Michael A. DiSpezio, you need:

  • a paper cup

  • a paper clip

  • a two foot piece of string (they say kite string, but we used regular sewing string)

  • and a needle

Tie one end of the string to the paper clip, and thread the other through the needle. Then, poke a hole through the top of the cup, and pull the string through...

...until the paper clip is tight against the top of the cup, and the string is hanging down, through the open end of the cup.

Wet the string.

Then hold the cup with one hand, and grasp the string lightly with your forefinger and thumb, just under the cup, pull down, and repeat.

As you run your fingers down the string, it vibrates. The vibrations move the air inside the cup, and the shape of the cup amplifies the sound. If you use your imagination a little, it sound like the cup is laughing.

It's great to be a homeschooler.


Christy Killoran said...

Neat experiment. I'm going to have to make a list of your experiments so that I can remember to try them.

Ticia said...

I bet they sat there forever playing with that cup.

Unknown said...

LOL! Sounds like the Crypt Keeper laughing! FUN!

Natalie PlanetSmarty said...

How interesting. I think I did something like this in physics class once. It does sound neat.

The Paisley Cupcake said...

That's great! What simple fun and learning experiences you create for your children.