Example, if you are holding an object in your hand that is spinning and you move your arm in a certain direction the object will feel heavier and in the opposite direction it will feel lighter. I assume it’s related to or caused by centrifugal force but have never heard a name for it.
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A spinning object has *angular momentum*, where it wants to keep spinning in the same direction. You can move it normally in any direction, but *rotating it* becomes very strange.
You see, momentum is a property of matter that describes its movement. A softball flying through the air has momentum, a stationary softball does not. Note that an object may have different momentums depending on your perspective, though that’s not important for this discussion.
For an example, a perfectly frictionless car on a flat road. You push gently on it for ten seconds, and it starts to slide forward slowly. You can go to the other side and push gently on it for ten seconds to stop it, or you could push harder for less time and also stop it.
This is because pushing harder changes its momentum faster.
*Angular* momentum is the same thing but for spinning objects. A spinning wheel takes force (or, more accurately, torque, the rotational version of force) and time to bring it to a halt. A faster and/or heavier wheel requires more force and/or time to get it started and stopped.
Momentum is conserved, though. If you took a clock and turned it around, it would spin the opposite direction, right? This means its momentum must have become the opposite of what it was before. I just said momentum is conserved – it cannot disappear – so something else must now have some spin in the original direction.
If you’re holding a spinning wheel and attempt to rotate it, you will feel that momentum from the wheel trying to spin you back. It will also resist turning, and try to turn itself at a different angle than the force you’re applying.
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