Here on Earth, friction is an unbalanced force that will cause moving objects to negatively accelerate. A top is a classically fun toy that spins for a period of time. Tops stop spinning because of friction forces between the top and the surface it is spinning on (as well as some friction with the air). Using a top that doesn't stop (available at Educational Innovations) and a normal top, this demo offers a discrepant event for students to experience. They know that all tops stop, but don't neccessarily know why, and they will be especially preplexed when they see a top that does not stop spinning. Watch the video to see it in action and to see why it doesn't stop spinning.
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