Does the gravitational force change for a spinning wheel

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Discussion Overview

The discussion revolves around whether a spinning wheel generates any change in gravitational force or lift, particularly in the context of its weight and behavior in a gravitational field. Participants explore the implications of spinning on the wheel's mass and the potential for lift in the presence of air, considering both theoretical and practical aspects.

Discussion Character

  • Exploratory, Debate/contested, Conceptual clarification

Main Points Raised

  • One participant questions if spinning a wheel generates lift, noting the torque force is directed downwards.
  • Another participant asserts that spinning does not change the mass of the wheel, and therefore it will accelerate in a gravitational field the same as a non-spinning wheel, assuming a vacuum environment.
  • A different participant raises the possibility of lift if the wheel spins fast enough in air, while acknowledging that the mass remains unchanged.
  • One participant agrees that a wheel can be designed to generate lift through rotation, similar to a helicopter rotor, but emphasizes that this does not reduce the gravitational force or affect mass.
  • Another participant argues that for a symmetrical wheel in a symmetric atmosphere, symmetry prevents the generation of upward or downward forces, despite the direction of rotation being a matter of convention. They mention a theoretical possibility of stable asymmetric circulation affecting lift direction.

Areas of Agreement / Disagreement

Participants express differing views on the effects of spinning on gravitational force and lift generation. While some agree that mass remains unchanged, there is no consensus on the implications of spinning in air and the potential for lift.

Contextual Notes

Participants discuss conditions such as the presence of air and the symmetry of the wheel and atmosphere, which may influence the outcomes of their arguments. The discussion includes assumptions about ideal conditions and theoretical possibilities without resolving them.

Mathijsgri
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When a wheel spins does it generate lift or something, the wheel spins so that the torque force is downwards.

for example you measure the weight of the wheel and then you spin then wheel does anything change?
The wheel is solid and if their change something does it matter if it is a constant velocity or an acceleration.
 
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No, spinning makes no difference to the mass of the wheel.
Hence it will accelerate in a gravitational field exactly the same as a non-spinning wheel.
(Assuming we are considering what happens in a vacuum that is - if air is present then the spinning might create some aerodynamic effects, but still the mass of the wheel won't change)
 
if their will be air and the wheel spins fast enough is their cab their be a lift force?
i know the mass won't change but what about the total downwards force?
 
Yes, the wheel could be intentionally designed to generate lift as a result of the rotation .
Essentially that's what a helicopter rotor does.
However this doesn't reduce the force of gravity or affect the mass.
It just produces a counter-force acting in the opposite direction.
 
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Mathijsgri said:
if their will be air and the wheel spins fast enough is their cab their be a lift force?
i know the mass won't change but what about the total downwards force?
For a symmetrical wheel in a symmetric atmosphere, the symmetry guarantees that there can be neither upward nor downward forces (*). The fact that the rotation [pseudo-]vector points downward is irrelevant. It is purely a matter of convention whether the rotation from a wheel spinning clockwise is seen as pointing toward the viewer or away from the viewer.

(*) There is a theoretical possibility that the rotation could set up a stable asymmetric circulation, but it would be a 50/50 chance which direction the asymmetry would point.
 

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