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.
In: 439
No for velocity (what we ordinarily think of as speed), yes for angular velocity (spinning speed).
You’re using the words a little interchangeably and that is causing your confusion. Spinning refers to the circular motion. Moving refers to traveling a distance. Spinning fast means that it turns all the way around more times that something spinning slower, in the same amount of time. So, no, the ball does not spin slower at different points, it is the same spinning speed all over the ball.
But the pieces the ball is made of (or think of it as locations on and in the ball, if you prefer), do travel through space at different speeds in order to have that same spinning speed. So, if you are straddling the axis of a merry-go-round, your feet move in a small circle in one rotation, while at the edge of the merry-go-round, the handles travel a much longer circle. Since that circle is so much longer but happens in the same time as your much smaller circle in the middle, its speed is clearly higher than your feet are going. So, edge is moving fast, but spinning the same speed.
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