Imagine a wheel. There are 3 ways this wheel can move. You could pick it up and walk it to a new location. You could pick it up and spin it without walking anywhere. Or you could roll it somewhere else.
When you pick it up and walk it, particles( on the top, directly in the middle, and directly at the bottom) all have the exact same velocity.
If you pick up the wheel and spin it, the particle on the top and the particle on the bottom have the same velocity just different directions.
If you roll the wheel: The particle in the middle will have velocity v. The particle on the top has to move with velocity 2v. This is because it has to move fast enough to get past the middle particle. If you really think about it and watch a wheel this part makes sense. But the last particle...the one on the bottom, that is where it starts to get weird. That bottom particle has a velocity of 0. That's right, ZERO!
Insane. It makes no sense at all unless you start thinking about the fact that if it had any velocity it would be spinning (like on ice) without getting anywhere. Does this make sense? It is crazy.
I hope this has made enough sense to blow your mind like it blew mine.
It doesn't blow my mind- then again, I did take physics as well- but it is quite interesting. I'm glad you're finding interesting things to keep learning exciting.
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