Imbalanced ball's affect on static friction

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Discussion Overview

The discussion centers around the relationship between linear force and static friction in a system involving a circle with a point mass attached, specifically when the circle rolls without slipping. Participants explore the dynamics of forces and torques in this scenario, considering various configurations and the implications of mass and size.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant inquires about the relationship between linear force and static friction as the circle rolls, suggesting that different force diagrams could provide insights.
  • Another participant questions whether the circle has mass and seeks clarification on what is meant by "linear force."
  • A suggestion is made to calculate torque in the system, with a note that gravitational attraction can be split into components.
  • A participant expresses interest in a generic case of a circle with radius r, indicating uncertainty about how size affects dynamics and focusing on smaller cases.
  • There is a discussion about how the point mass generates torque on the circle, with a focus on the force vector's components and their contributions to torque.
  • One participant clarifies that "massive" refers to whether the point mass has mass, suggesting that without mass, the point mass would fall vertically and not interact with the circle as expected.
  • A later reply acknowledges the oversight regarding the mass of the circle, confirming that it does indeed have mass.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the dynamics of the system, with multiple competing views and uncertainties regarding the effects of mass and the interplay of forces.

Contextual Notes

There are limitations in the discussion regarding assumptions about the mass of the circle and the point mass, as well as the definitions of forces involved. The implications of size on the dynamics remain unresolved.

Disgrntld
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Given a circle with a point mass attached, what is the relationship between the linear force and the force of static friction as it rolls without slipping? Each force diagram I made (http://imgur.com/a/xK8i1) seems a plausible place to start: a makes no torque, b makes no linear force, c makes no static friction.
 
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Is the circle massive? What do you mean by "linear force"?
 
I would try to calculate torque in the system of the circle.
There are many ways to split the gravitational attraction in two parts.
 
MikeyW, I'm interested in the generic case, just some circle of radius r. I honestly don't know how the size would affect it, but if the dynamics of the system change past some massive size, I'm interested in the smaller case. By linear force, I meant forces parallel to the slope of the ground that would result in sliding if there was no friction.

mfb, ok, so if I try to focus on how the particle generates torque on the circle, I'm thinking it would be easiest to split the force along the line through the center of mass like this (http://i.imgur.com/Ip7n7.png). The force vector perpendicular to a multiplied by r gives us the amount of torque. However, what do I do with a now? It causes no torque on the circle, but it's not parallel to the slope.

What I really want to understand are the interplay of forces here that would allow a situation like this (http://i.imgur.com/XpZPu.png) to have no angular or linear acceleration.
 
"massive" refers to "does it have mass", not its size. I think without any mass, your pointmass would simply fall down vertically until it reaches the slope (and the circle moves away in an undefined way) and continue sliding afterwards.
 
Oh, yes, the circle has mass. That was silly of me.
 
Last edited:

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