Piece of Cement in a Rotating Cement Mixer

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Discussion Overview

The discussion revolves around the dynamics of a piece of cement in a rotating cement mixer, specifically addressing whether it can travel at constant speed and the forces acting on it. The scope includes theoretical considerations of forces, motion, and the effects of rotation.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions if a piece of cement can travel at constant speed in a rotating mixer, noting the gravity vector and normal force acting on it.
  • Another participant introduces the idea that the Coriolis effect complicates the resolution of forces within the mixer.
  • A later reply reiterates the concern about the Coriolis effect, specifying a free body diagram relative to the ground.
  • One participant suggests that friction with the wall of the mixer is necessary for the cement to maintain motion, implying that without friction, the cement would remain at rest.

Areas of Agreement / Disagreement

Participants express differing views on the forces at play and the role of friction, indicating that multiple competing perspectives remain unresolved.

Contextual Notes

The discussion does not resolve the complexities of the forces involved, including the assumptions about friction and the Coriolis effect, which may depend on specific conditions within the mixer.

tahayassen
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Is it possible for a piece of cement in a rotating cement mixer to travel at constant speed?

If we graph a cement mixer (circle) on the Cartesian plane with a radius of 1, then at (1, 0), there would be a gravity vector pointing down and a normal force pointing towards (0, 0). Are there any other vectors that can cause the net force to point towards the centre of the cement mixer (to cancel out the gravity vector)?
 
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The problem of resolving the forces in a cement mixer is complicated surely by the coriolis effect through the medium from the centre to the perimeter
 
tony_physic said:
The problem of resolving the forces in a cement mixer is complicated surely by the coriolis effect through the medium from the centre to the perimeter

I'm referring to a free body diagram relative to the ground.
 
tahayassen said:
Is it possible for a piece of cement in a rotating cement mixer to travel at constant speed?

If we graph a cement mixer (circle) on the Cartesian plane with a radius of 1, then at (1, 0), there would be a gravity vector pointing down and a normal force pointing towards (0, 0). Are there any other vectors that can cause the net force to point towards the centre of the cement mixer (to cancel out the gravity vector)?

Friction with the wall. Without friction the cement will just be at rest and the mixer will rotate nicely around it.
 

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