Recent content by zwillingerj

OK, great, I think I've got a fairly good handle on this now. Turtlemeister, your suggestion to ignore the "hard to quantify forces" is a very good idea, and makes the concepts much easier to understand. Thanks for all the help, everyone!

Thanks TurtleMeister, this is a very clear explanation. To change gears, you surmised (from an earlier post) that the friction for the more massive marble will be greater, and thus the smaller marble will travel further. It seems Bob S reaches the opposite conclusion -- the friction will...

For a solid, uniform dense sphere, I = 2mr^2/5. This would imply that a more massive object, or an object with a larger radius (or both), will have a higher moment of inertia. This seems to imply that a more massive marble, or a marble with a larger radius (or both), will accelerate slower...

Bob, thanks for the clear response, and Jeff, thanks for your thoroughness. I get this part, except re: truck vs. car, isn't drag a retarding force, so wouldn't the increased drag work against the truck? Jeff, I wasn't sure how to fully parse your earlier answers - do you agree with Bob...

Thanks, Jeff. Let's assume now that both marbles have the same radius, but one is more massive than the other. That is, try to remove the factor of the larger marble reaching the bottom sooner because it's radius is larger, as illustrated in your graphic. Both marbles would then reach the...

Thanks Bob, I appreciate the help. I'm a bit confused: is what you said equivalent to saying that if the two balls are rolling, the heavier ball will reach the bottom with a great velocity than the lighter ball, and will thus propel it further? (And the opposite case, if the balls are slipping...

Thanks for all the help thus far, but I don't believe anyone has answered the question yet. I am not trying to determine if the balls will slide vs. roll. I'm trying to understand the principal of interia While slide vs. roll, coefficient of friction, friction vs. drag, etc. all might...

I thought it was agreed that, if we assume gravity is the only force acting on the marbles as they roll down the hill, the balls will have the same speed when they reach the bottom of the hill?

I apologize for the non-technical terms, for this question assume "resistance" = rolling resistance = rolling friction = rolling drag = whatever force you want to call it that actually slows spherical objects down as they roll. This is the question: Go to some actual hill. Place two...

The force of friction slows the balls down. In the first experiment, both marbles have the same friction force working against the marbles (F_f marble 1 = F_f marble 2). In the second case, the more massive marble has a great friction force, because it it more massive, so the normal force is...

I understand the marble won't roll without friction. The point is not to ignore friction entirely -- then the question is meaningless -- but in the first case, to assume that the friction for the two marbles is constant, and for the second case, to closer simulate reality by allowing the...

I have a very simple conceptual physics problem that I am looking to solve, and unfortunately I've been out of school a little too long to solve: Suppose you have a hill, and at the bottom of the hill it levels off and keeps going on. You take two marbles of different masses and roll them...