Chanukah science...spinning tops

What do bicycles, frisbees, yo-yos, hula hoops, dreidels, and even the earth have in common? They all spin, and so long as they spin the better they are at resisting what gravity is trying so hard to get them to do, which is tumble and fall.

This week we talked about how dreidels work and then we observed the optical illusions produced by spinning tops with different colorful patterns. We finished up by making our own tops using old CDs.

Physics: You spin me round round baby round round

What do bicycles, frisbees, yo-yos, hula hoops, dreidels, and even the earth have in common? They all spin, and so long as they spin the better they are at resisting what gravity is trying so hard to get them to do, which is tumble and fall. This week in physics, we played dreidel with a twist. Instead of playing dreidel for gelt, we played dreidel WITH gelt. The kids prepared 3 dreidels as follows: Each one had a plate with 4 coins attached either at the center or at the periphery in one of two possible patterns. The goal was to see which distribution of weight allowed the dreidel to spin the longest. Here's your clue: How is the weight distributed on a bicycle wheel? Is more of it at the center or along the periphery?

Physics: What color is it really?

This week we did 3 mini-experiments to investigate how we perceive color. The first was with spinning color wheels. The kids compared the patterns of the discs when still to the patterns they saw when the discs were spun. The second mini-experiment involved looking at magazine pictures under the microscope and comparing the images seen with the naked eye to the colors seen at greater magnification. The third was simply giving each kid some red, blue, and yellow paint and letting them go wild...well on paper anyway.

When we physically combine red, blue, and yellow paints in different proportions we can create an enormous range of colors. Similarly the human brain will combine colors that your eyes see when those 2 colors are seen in rapid succession, as in the case of the spinning color wheels or when they are placed very close together, as revealed by a microscopic examination of pictures from a magazine. What is especially cool about the magazine pictures is that no matter what color you "see," when examined under the microscope you realize that the image is made up of just 3 colors: magenta, cyan, and yellow (aka red, blue, and yellow). By producing images that include different ratios of the primary colors, you can get just about any color.

Physics: You spin me round round...

What do bicycles, frisbees, yo-yos, hula hoops, dreidels, and even the earth have in common? They all spin, and so long as they spin the better they are at resisting what gravity is trying so hard to get them to do, which is tumble and fall. The tendency of an object to resist change, is called inertia, or in the case of something spinning, rotational inertia. This week the kids were given plastic plates of different sizes, sticks, and weights (in the form of kippa clips) and were challenged to design the dreidel with the greatest rotational inertia...that's fancy talk for the dreidel that can spin the longest.