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Q & A: Spinning objects releasing mass?

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Most recent answer: 10/22/2007
Q:
does a spinning object release a type of mass in the direction of the spin giving it angular momentum. (Explains why a fast moving top holds steady and a slower moving top wobbles, non-spinning top falls down) If so, if the mass released by the spin motion exceeds the amount of mass exerted by the gravity exerted on it, can it float?
- glenn
los angeles, ca USA
A:
Hi Glenn,

No, most spinning objects hold together rigidly while they are spinning. Some objects will fall apart if you spin them too fast, but they are either just too loosely held together or cracked or otherwise easily break apart.

Angular momentum does not depend on mass being ejected from a spinning object. Tops which are spinning wobble because of a phenomenon called precession. Here is  on our web site covering precession, and also the subject of at for another description of how precession works.

The faster an object is spinning, the more angular momentum it has, and the more torque it will take to change this direction, making bicycles more stable at higher speeds, and tops also more stable at higher speeds.

The force of gravity tugs on all objects and some force is always needed to counteract it, or an object will fall. Some demonstrations involving spinning bicycle wheels or gyroscopes on long poles seem to defy gravity because the upwards force is applied at a point rather far away from the center of mass. But the force has to be applied somewhere, and the turning motion is governed by the the fact that the is the rate of change of angular momentum.

Tom

(published on 10/22/2007)

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