How is energy transferred from the bicycle wheel?

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    Bicycle Energy Wheel
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Discussion Overview

The discussion revolves around the mechanics of energy and angular momentum transfer when a bicycle wheel is flipped on a turntable. Participants explore the relationship between the bicycle wheel's motion and the resulting rotation of the turntable, questioning how energy is involved in this process.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants assert that energy is not transferred from the bicycle wheel to the turntable, but rather angular momentum is involved.
  • Others question where the turntable obtains the energy necessary for its rotation, suggesting it comes from the man's muscles.
  • A participant notes that the man must apply force to the axle of the wheel to turn it, indicating a connection between the man's actions and the resulting motion of the turntable.
  • It is mentioned that the forces or torques involved are responsible for transferring angular momentum, but not energy, from the wheel to the turntable.
  • One participant raises a scenario where the wheel is flipped back, questioning the fate of the energy and suggesting that the man must exert effort again, indicating a potential loss or transformation of energy.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the role of energy in the interaction between the bicycle wheel and the turntable. There are competing views regarding whether energy is transferred or if only angular momentum is involved.

Contextual Notes

Participants reference hypothetical scenarios, such as standing on frictionless ice or in space, to illustrate how the motion might differ under various conditions, indicating that the discussion is context-dependent.

Michio Cuckoo
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https://www.youtube.com/watch?v=V3UsrfHa4MQ

So check out the above video.

When the man flips the bicycle wheel over, the turntable he is sitting on starts to rotate. What I don't understand is, how is energy transferred from the bicycle wheel to the turntable?
 
Last edited:
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Michio Cuckoo said:
What I don't understand is, how is energy transferred from the bicycle wheel to the turntable?
Energy isn't transferred from the bicycle wheel to the turntable. Just angular momentum.
 
Last edited:
A.T. said:
Energy isn't transferred from the bicycle wheel to the turntable. Just angular momentum.

But where does the turntable get the energy to rotate?
 
Michio Cuckoo said:
But where does the turntable get the energy to rotate?
From the muscles of the man.
 
In order to turn the wheel through a right angle, the man must apply force to ends of of the axle. You can trace trace the reaction force through the man's muscles and skeleton to his feet braced on the turn table (obviously, if he were standing on frictionless ice or in space, the motion would be different.)
 
HallsofIvy said:
In order to turn the wheel through a right angle, the man must apply force to ends of of the axle. You can trace trace the reaction force through the man's muscles and skeleton to his feet braced on the turn table
Yes, the forces (or rather torques) are transferring angular momentum from the wheel to the turn table. But there is no energy transferred from the wheel to the turn table.
HallsofIvy said:
(obviously, if he were standing on frictionless ice or in space, the motion would be different.)
On ice it would be quite similar to the turn table.
 
HallsofIvy said:
In order to turn the wheel through a right angle, the man must apply force to ends of of the axle. You can trace trace the reaction force through the man's muscles and skeleton to his feet braced on the turn table (obviously, if he were standing on frictionless ice or in space, the motion would be different.)

quite a sneaky transfer of energy. Thanks for explaining.
 
So what happens if he flips the wheel back again? Presumably the man has to work just as hard, but now the turntable stops. Where has the energy gone?
 

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