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The Physics of Those Playground Spinny Things (plus FAIL VIDEOS!)



Yay for more circular motion! So does anyone know what I'm talking about when I say "playground spinny things"? There like mini merry go rounds for playgrounds, but like...without the animals and cheesy music. Someone goes on them and you spin them really fast? There are funny fail videos on the internet of people spinning super fast on them and then flying off? Sound familiar?

I hope so, because I really don't know what they're called. But anyway, I thought I'd talk about the physics behind them for a bit.

So when you spin on these spinny things, you feel a centripetal force (Fc) and centripetal acceleration (ac) point towards the center of the circle. The centripetal force, Fc, is equal to mv2/r, and remembering Newton's 2nd Law (F=ma), we can then deduce that ac = v2/r.

If, like the people in those fail videos, you were to spin so fast that you flew off the spinny things - you would fly off in a path tangent to the circle. This is because your velocity acts tangently to the circle.

There's something I don't quite get about this, though. When you spin, you feel like you're being pulled outward away from the center of the circle...if Fc is pointed toward the center of the circle, why do you feel a force outward instead? Maybe I'm just thinking about it wrong, but either way it'd be great if someone could explain that to me.

Thanks for reading! I hope you enjoyed a snippet of the physics behind those playground spinny things I still don't know the name of.

Until next time,

bazinga818 :ass:

EDIT: I guess they're actually called merry-go-rounds too? Weird. Anyway, I found a nice fail-compilation video for you to enjoy below. For some reason people seem to think it's a super awesome and profoundly intelligent idea to take a motorcycle wheel to these things...makes for a good video anyway! Yay circular motion! :lol:

My favorite is probably the one at 1:23...that kid just goes downnnn, man. Like come on it wasn't even going that fast. What a pansy.

And I really realllllly want to try the one at 1:51, minus the faceplant part.

I also thoroughly enjoy the duck one.

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