Rolling ball, change of direction

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Discussion Overview

The discussion revolves around the dynamics of a free-rolling ball on a plane when lateral forces are applied. Participants explore the effects of these forces on the ball's trajectory and its axis of rotation, considering concepts such as friction and gyroscopic effects. The scope includes theoretical reasoning and conceptual clarification.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant proposes a scenario where a lateral force is applied to a rolling ball, questioning the resulting path and changes in the axis of rotation.
  • Another participant suggests that applying a force at the center of mass (CoM) implies the necessity of friction, and notes that the interaction of friction with gyroscopic effects could lead to complex and counterintuitive outcomes.
  • A third participant inquires about the expected changes in trajectory due to the applied forces, prompting further exploration of the dynamics involved.
  • A later reply speculates that the gyroscopic effect might assist in turning the ball towards the East, suggesting a possible North-East trajectory, while expressing uncertainty about the axis of rotation remaining flat.

Areas of Agreement / Disagreement

Participants express differing views on the effects of lateral forces and gyroscopic effects on the ball's motion, indicating that multiple competing perspectives remain without a consensus.

Contextual Notes

There are unresolved assumptions regarding the nature of the forces applied, the role of friction, and the specific conditions under which the ball is rolling. The discussion does not clarify the mathematical relationships governing the motion.

Who May Find This Useful

Individuals interested in dynamics, physics of motion, and the effects of forces on rolling objects may find this discussion relevant.

jonbarril
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Say I have a magic way to exert lateral forces on a free-rolling ball on a plane, with no slipping. Say I apply a force for a given period from the South, the ball starts rolling to the North and attains a constant speed. Then I suddenly apply the same force for the same period but from the West. What is the resulting path of the ball on the plane? What is the path of the balls apparent axis of rotation (how does it change from East-West to eventually North-South, does it remain horizontal)?

Thanks
--jon
 
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If you apply just a force at the ball's CoM, and it starts rolling, the you must have friction. If you then apply the lateral force you will have an interaction of friction gyroscopic effects, which can get quite complex and counter intuitive:

 
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Forces are associated to accelerations.
How do you believe the trajectory will change?
 
It has been a long while since I took physics. I think the gyroscopic effect will work in favor of helping to turn the ball to the East. My guess is that the ball would end up rolling North-East. Not sure if the axis of rotation would stay flat. This is all complete conjecture. I'm hoping folks out there can give a more informed description of the ball's motion.
 

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