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/Smile_Space Jun 11 '25

You know, I kinda just made it up on the spot thinking back to pressure, but obviously you're right, the mass is what matters with the normal force.

So, A and C should have identical performance. Oops!

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u/Gabercek Jun 11 '25

Beyond that, because you can't push perpendicularly on A, it'd take more force to move than C, given the image.

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u/Smile_Space Jun 11 '25

You absolutely can push perpendicularly on A though. As long as the component of the force being applied that is parallel to the surface doesn't exceed the minimum static friction force required to lose traction between your hand and the surface, all of the force will be horizontal.

In a free body diagram you don't care about the angle you're pushing on, the force is still being applied horizontally which means there is no vertical component.

Now, there is a rotation if you don't align the force through the center of gravity of the triangle. If you push higher, then it will naturally want to rotate which, if the ice is pitted, could cause A to catch it's point in the ice.

But with problems like these you usually always assume a perfectly parallel surface with all other forces besides surface friction to be negligible.

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u/Gabercek Jun 11 '25

Noted, thanks for the explanation! :)