I understand why it needs to exist, otherwise the Earth wouldn’t keep spinning, coins would fall over immediately when you tried spinning them, artificial gravity wouldn’t be possible, etc. But I’m not sure how it works out physically. (nb. I’m talking without regard to drag, friction, etc. For example out in space where those are negligible factors.)
By definition, a spinning object is under acceleration (individual points on the object are constantly turning around the center of rotation, which is a form of acceleration in linear physics). And force requires energy, so why doesn’t the spinning of an object expend its angular momentum and slow it down over time?
Along the same vein, how does artificial gravity work in this context? As I understand it, centrifugal force is a fictitious force, but if I am inside a spinning object I am still being pressed against it as it turns and subjected to acceleration (from an observer’s point of view, at least). And so since I am being accelerated, something has to be using energy to accelerate me, right?
I apologize if I am sounding stupid but this has been wracking my brain for the last while and I’m desperate to figure out the answer. Thank you for any help!
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Eeeh though one to explain but let’s try.
A spinning object doesn’t accelerate as long as no forces are applied and the inertia stays the same. The acceleration you are mentioning is only there when changing the height relative to the center of rotation. Which doesn’t happen on the earth or in a coin.
However
Imagine an figure skater spinning with wide arms. The moment their arms come closer to the center of rotation. The rotation will speed up. Once widening the arms again. The rotation slows back down. This happens because of the energy staying roughly the same, but the moment of enertia decreases and increases again (how hard it is to rotate the object). But no energy has been lost doing so.
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