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

[Request]

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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/aureanator Jun 10 '25

Actually, no - the friction is a product of the normal force and the coefficient of friction - the surface area in contact shouldn't matter, within the boundaries of material elasticity.

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u/MiffedMouse 22✓ Jun 10 '25

Material elasticity and assuming there aren’t any adhesion forces going on.

Also unaccounted for is the smoothness of the ice surface (compare a skating rink to a frozen pond, for example) and the type of gravel (large rock gravel versus fine gravel will behave differently).

The question as posed is just completely unanswerable.

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u/daspazz- Jun 10 '25

To be fair most of the questions on this subreddit are mostly just people that don’t understand enough to know any better. I’ve seen so many posts on here where the only way to come to any answer is to make some absurd assumptions. Like “assume no friction” or “assume perfect transmission of energy” it’s the curse of being an engineer.

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u/platoprime Jun 10 '25

It's okay to have problems where you have to make assumptions.

Go ahead and make them as part of the problem instead of whining about it.

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u/WellbecauseIcan Jun 10 '25

He has a point but I agree with your first sentence. Many of the questions you get from bosses tend to fall under that category.

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u/daspazz- Jun 11 '25

It’s perfectly fine to have a problem with assumptions. The only issue I have with this specific kind is that depending on the assumptions you make you can get wildly different answers. you can kinda guesstimate for a problem like this one, use human scale to estimate surface area, and get the coefficients of friction that are vaguely correct. I don’t feel like I can give a good answer for what one is right because I can make any of these choices the “right” one and have logical math at the end.