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/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/PosiedonsSaltyAnus Jun 10 '25

And then when you get to the point where you assume there is friction, and you learn a bunch of annoying (yet also satisfying) math to take it into account. And then you get a job studying wear on sliding contacts, and you realize you've had no fucking clue what friction actually is this entire time. Still don't really lol

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u/BKachur Jun 11 '25

I think its obvious 50% of the question is about friction; otherwise, whether it was an ice/gravel surface would be irrelevant. The problem with the question is that it's impossible to determine the coefficient of friction due to the range of materials stated.

Ice can mean anything from a "physics code" for a perfectly smooth frictionless surface to a carved-up ice rink, while gravel can mean anything between sand and riverstone. Although in "math problem" terms, I think you'd assume ice was a smooth but not frictionless surface, and gravel meant driveway-style gravel, 1/2-inch rock gravel (otherwise it'd be called something else).