Cylinder on a frictionless inclined plane

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Discussion Overview

The discussion centers on the behavior of a cylinder on a frictionless inclined plane, specifically whether it spins or rolls as it descends. Participants explore the implications of friction and gravitational forces in this scenario.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • Some participants propose that a cylinder on a frictionless inclined plane will not spin as it comes down, suggesting that it will simply slide without rolling.
  • Others argue that a frictional force is necessary to provide the torque needed for the cylinder to start spinning about its center.
  • A later reply clarifies that since the gravitational force acts through the center of mass, there is no torque generated, leading to the conclusion that the cylinder will slide rather than rotate.
  • Another participant emphasizes that all forces acting on the center of mass and the absence of friction results in sliding motion.

Areas of Agreement / Disagreement

Participants generally agree that without friction, the cylinder will not roll and will instead slide down the incline. However, there is some debate regarding the role of torque and the conditions under which the cylinder might begin to spin.

Contextual Notes

The discussion does not resolve the implications of different initial conditions or the effects of introducing friction, which may alter the behavior of the cylinder.

jp
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I just have a question about cylinder. If a cylinder is on a frictionless inclined plane, does it spin as it comes down? I guess on a level surface, frictional force is required for a cylinder to roll, but I'm not sure about inclined plane.
 
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Originally posted by jp
If a cylinder is on a frictionless inclined plane, does it spin as it comes down? I guess on a level surface, frictional force is required for a cylinder to roll, but I'm not sure about inclined plane.
If the cylinder is started from rest, it will just slide down without rolling. A friction force is required to exert the torque needed to start it spinning about its center.
 
More precisely, since gravitational force acts on every point of the object, it is the same as if it acted only on the "center of gravity"- since the net force is through the center of gravity there is not torque and so no rotation.
 
Since all the forces are passing through COM and there is no physical interaction due to friction hence it must slide
 

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