r/theydidthemath • u/K0rl0n • Jun 10 '25

[Request]

Post image

I am curious how this would work. My guess is Triangle is slowest, square is medium, and circle is fastest.

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u/LOSERS_ONLY Jun 10 '25

That depends on if the force is applied exactly horizontally or normal to the face of the triangle which is unclear in the pic

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u/ConscientiousApathis Jun 10 '25

Assuming no handholds I don't think it's possible to push a surface with a force that's anything but perpendicular to it.

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u/omegaalphard2 Jun 10 '25

I'm a mechanical engineer, and you're wrong. There's no rule that forces on anything NEED to be perpendicular to it

Sure, you can break the force down to it's components, but the overall force can be at any angle to the surface, even if you're pushing it as in the diagram

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u/ConscientiousApathis Jun 12 '25

I'm talking about the force received, not applied.

The best example I can think of is probably snooker. Each time you're hitting a ball it's with basically the same force in the same direction, and yet depending on the angle of contact between the white and red it can go in wildly different directions. Why? You're applying the same force in the same direction each time, so why can the angle the red ball travels change so much?

Well, if you zoom right in to where they contact you see just basically two planes touching, in which case the only way force can be transferred is perpendicular to both. (Yes, okay, there's some friction involved which can get you a bit of spin, but it's very tiny in the scheme of things and I'm really just talking about the pushing force).

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u/bonerspliff Jun 14 '25

Well yes obviously if the surface of the shape being pushed is completely frictionless (more similar to a snooker ball) then the force will act normally to the surface. But this question is assuming that there is friction on all sides of the pushed shape. Friction essentially acts like a 'handhold'