Thread: The weight of a spinning top

Does a spinning top weigh less than the unspinning top? Yes it does. We could try this as a spinning electric motor and the same circuit switched off. Can we determine a relationship between the weight loss amount and the speed of rotation?

Originally Posted by Joshua Stone

Does a spinning top weigh less than the unspinning top? Yes it does.

No it does not. Claims to this effect have been made by various persons from time to time. No experimental work supporting the claim has ever been duplicated. I know of no theoretical explanation that would produce this result.

If you are aware of any experimental evidence that has been confirmed, please provide citations.

As I mentioned in the 'weight of a tensioned rod' thread- if you aren't adding any more mass (or taking away) to an object, then the weight doesn't change unless if the object is entered into a different gravitational field strength (g) environment.

I wonder if a spinning top doesn't weigh just a trifle more than at rest, because of relativistic effects and the energy/mass equivalence. The latter might also work for the tensioned rod.

In either case, the increase of mass would be so small as to be extremely dificult to detect; don't bother to try using your $20 kitchen scale.