Science of the circus

Close your eyes and imagine that you are at a circus. Can you smell the popcorn? Can you hear the elephants? Open your eyes and what do you see? Flashing lights and bright colors! Clowns and circus performers. There are some truly amazing sights at a circus!

Attach a different color of cellophane to each of the flashlights with a rubber band. Shine the green flashlight onto the plain white surface. In your other hand, hold the blue flashlight so that it is shining right at the same part of the white surface as the green flashlight is shining at. Have your helper hold the red flashlight so that it shines in the same place as the two flashlights you are holding.

Adjust the flashlights (you may need a second helper to hold a flashlight) until you see bright white light shining on the white surface. Try sticking your hand between the surface and the colored lights. What colors do you see? Try to count them. Experiment with the three flashlights by shining two of them at once. What do red and blue light look like together? How about red and green? Green and blue?

What Happened: Did you know that all white light (the kind from a desk lamp, ceiling fan, and the sun) is actually made of many colors? For a light show at the circus colored filters break up the white light into colors like red, blue, and green. A filter is a colored piece of plastic or glass that only lets light of that color through.

For example, a green filter turns white light into green light. In this project, you made your own filters using cellophane. Using red, blue, and green lights you can combine them in just the right way so that it turns into white light. Light mixes in different ways than crayons or markers do. The more colors of crayons you mix, the darker your picture ends up looking. With light, it’s the opposite. The more colors of light you add, the brighter it seems to be.

How do the circus performers fly through the air like that? Well, acrobats have to train for many hours just like athletes. They practice a lot before their big performance. Acrobats like tight rope walkers and trapeze swingers also use a kind of science called physics to help them. Physics is the study of force (pushes and pulls) and motion (how things are moving).

Sometimes on the trapeze one acrobat will catch another mid-air. To be able to catch hands in the middle, they have to time their swings just right. For example, the acrobat with the shorter rope will have to swing out slightly after the acrobat with the longer rope.