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Name: Denise
Status: educator
Age: N/A
Location: OH
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Date: N/A

I have a very curious 5 year old who loves to figure things out. His favorite toy right now is a Gyroscope. (This is the 5 year old who asked me today: "Does energy create electricity or does electricity create energy?") He wants to know how it works. He is trying to figure it out and thinks that the air from the spinning rotor is causing it to turn. The one we have looks somewhat like a top and has an alloy ball peg on the end which sits on a small pedestal. Is there an easy, detailed (he loves details!) was to explain to him how a gyroscope works?

Wow!! You have a 5 year old who is asking some very basic questions that (so far as I can find) do not have 5 year old answers, but that is the challenge. I will start, but I do not think that I will have the last 'answer' on my first try. First, eliminate the air. Yes, that is what you feel, but that is friction that tends to cause the gyroscope to slow down. The motion of a gyroscope is far more abstract than that. When you start an object (the gyroscope) spinning it "wants to keep" spinning in the same direction and with the same "energy" it has when you start it spinning. It will slow down due to friction, but the principle is that in an ideal situation it would keep spinning at the same "speed" and the same direction that it starts out with. What determines the speed is the amount of matter (mass) that is off center from the axis (direction) around which the spinning axis (direction). Here, an example that is available on TV is an ice skater at the Olympics in Italy. As the skater brings more of her/his mass toward the axis of spin the speed of rotation increases. If the mass (you can call it weight) is not exactly the same as the axis of spin, the spinning "thing" tries to return to the beginning direction. But because the direction that it is off the perfect axis is "left and right" and "backwards and forwards" the gyroscope will spin in a circle trying to "find" its perfect axis. If I were trying to explain this to a 5 year old, I would pause here and see what questions this (incomplete explanation) response brings. It is questions like this from a 5 year old that brings scientists to our collective knees. How to "explain" the conservation of angular momentum in the language of a 5 year old. Start with this, but it is by no means adequate. Sorry for a -- not so good -- explanation.

Vince Calder

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