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- Thread starter damo_clark
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I do not quite understand what you are asking, a sketch or a re-explanation could help, but keep in mind the above statement. Also think about what determines the direction of spin in a sink of emptying water...

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russ_watters

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Yes. Provided there is no net external torque the initial angulur momentum will be conserved - in both magnitude and direction.Thanks Russ, I thought that might be the reason. Just a follow up question.... If I spun a wheel in space, say a bicycle wheel, would it keep spining in the initial plane that I set it in motion.

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Meir Achuz

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This effect is explained in most intermediate level Mechanics books.

Using Euler's equations for rotation about principle axes, you can show that the axis of rotation is stable for rotation about the longest and shortest dimension, but unstable for rotation about the intermediate axis. It is demonstrated most clearly with a book. Use a string to keep it from opening. When tossed rotating about its long or shortest axis it

spins without flipping, but acts like your fork if it is spun about the intermediate axis.

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Doc Al

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This effect is often called the "Tennis Racket Theorem", derived as

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