eli5 Does every part of a ball spin at the same speed?

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I was holding a rubber band ball in my hand earlier and tossing it up in the air at about eye level. I noticed that I could see the shape of individual rubber bands on the axis of rotation on the outside of the ball but the edges of the ball were blurry. This got me thinking.. is a ball spinning slower near the axis than it is at the outer edge? Is the earth spinning faster at the equator than it is at the poles? If speed is d/t then the math makes sense to a layman like me that the ball would be rotating slower at the center and faster on the edges. Please help.

edit: holy shit. balls are fascinating.

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Anonymous 0 Comments

That would depend on what you mean by “speed”. “Speed” usually refers to how far something travels in a given time, but it can also refer to how much it rotates in a given time (angular speed).

Every part of the ball has the same *angular speed*. It’ll take the same amount of time to complete one revolution. Not every part will travel the same distance in the same amount of time.

On Earth, this means that a day is the same length of time no matter where you are. Whether you’re in the arctic, the tropics, on top of a mountain, or deep below ground, a day is the same amount of time. However, the distance you travel over a given time period will depend on where you are. You’re fastest at the equator, you’re stationary at the poles. You’re fastest on a high mountain, you’re stationary at Earth’s core. If you’re on the rotational axis, you’re stationary, and you’ll move faster the farther you are away from it.

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