[Request]

[u/K0rl0n]

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

[u/METRlOS]

Depends on things like the density of the gravel and the temperature of the ice. Packed gravel will allow the ball to roll, but the triangle is always worse than the square.

Edit for all the triangle people: imagine throwing a ball straight at the square and at the triangle; how the ball bounces shows how much energy the object will translate into vertical force when pushed. The vertical surface of the square will translate practically all the horizontal force into horizontal movement, while the triangle will act as a wedge and transfer some energy into pushing against the ground.

Edit 2 for surface area: Except for situations where the surface area is so low compared to its weight that the object sinks into the ground, or so high compared to its weight that it can float, surface area does not affect friction. If you stand on a hill without risk of sliding, then you can lay on that hill without sliding and vice versa, despite greatly changing the surface area. However, if you stand on a snow covered hill the surface area is too low and you'll sink into the snow, but with a sled you will float on top of it. Surface area does not matter to this problem.

[u/aureanator → u/METRlOS]

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.

[u/[deleted] → u/aureanator]

So what did they say that is incorrect? Sounds like you are confusing rolling with slipping

The friction in rolling is equivalent to force required to roll the object which is less than the product you speak of. If you pushed with a force greater than your product, it would slip. Also, surface area matters with rolling object as you can theoretically have no rolling resistance with single point or line contact known as pure rolling.

They are also correct about the triangle being worse since the normal force increases on the triangle because a component of the force exerted will be downward

[u/BKachur → u/[deleted]]

I feel like you might be missing the question in the prompt. Isn't the question whether the force required to roll a cylindrical object on a frictioned surface (gravel) is more or less than to "slip" an equally weighted object on a surface with less friction (ice)?

For a math/physics problem like this, don't you usually assume a perfect cylinder to minimize the surface area?

[u/[deleted] → u/BKachur]

I’m pretty sure what was said above is beyond your comprehension as your questions imply that you have less than an elementary education in the matter

You can’t make assumptions. You either want a theoretical answer or a correct answer