What Causes a Sphere to Rotate on a Ramp with Negligible Friction?

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  • Thread starter Thread starter Kiwiro0ls
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Discussion Overview

The discussion centers on the mechanics of a sphere positioned at rest on a ramp with negligible friction, specifically exploring the conditions under which the sphere would rotate as it descends the ramp.

Discussion Character

  • Conceptual clarification, Debate/contested

Main Points Raised

  • One participant suggests that with only gravity and the normal force acting on the sphere, both of which pass through its center of mass, there would be no net torque to cause rotation.
  • Another participant questions the assumption that the sphere would rotate at all under these conditions, implying that rotation may not occur without friction.
  • A third participant expresses a belief that rotation is impossible without friction, indicating a lack of motion in that regard.
  • A fourth participant agrees, stating that without friction, the sphere will simply slide down the ramp without rotating.

Areas of Agreement / Disagreement

Participants generally agree that without friction, the sphere will not rotate and will instead slide down the ramp. However, there is some debate regarding the initial conditions and the implications of negligible friction on rotation.

Contextual Notes

The discussion does not resolve the underlying assumptions about the nature of forces acting on the sphere or the definition of negligible friction.

Kiwiro0ls
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If I have a sphere at rest on top of a ramp, if friccion is negligible, the only forces acting on it would be gravity and the normal force. Both of these go through it's axis of rotation which would be the spheres center. What would cause the rotation then so τ≠0?
 
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Kiwiro0ls said:
What would cause the rotation then so τ≠0?
What makes you think it would rotate?
 
I guess there's no rotation at all unless there's friccion? boo...
 
Right. Without friction, the sphere will just slide.
 

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