Can a Water-Filled Flywheel Generate Extra Energy While in Motion?

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Discussion Overview

The discussion centers around the concept of whether a water-filled flywheel can generate extra energy while in motion. Participants explore the implications of filling a flywheel with water and the resulting effects on energy and momentum, considering both theoretical and practical aspects.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant proposes that filling a flywheel with water while in motion could potentially gain energy.
  • Another participant argues that filling the flywheel would result in a loss of energy due to friction causing the water to start moving, which would slow down the flywheel.
  • A third participant reinforces the idea that energy would decrease, stating that the momentum remains constant while the net energy decreases as the flywheel slows down.
  • In a different scenario, a participant suggests that if the flywheel's walls are frictionless and the water is initially still, deploying vanes could accelerate the water to flywheel speed without energy loss, preserving energy and momentum.
  • A later reply acknowledges the consideration of kinetic energy, noting that while kinetic energy would decrease, heat would increase in the system.

Areas of Agreement / Disagreement

Participants express differing views on the energy dynamics of the water-filled flywheel, with no consensus reached on whether energy can be gained or lost in this scenario.

Contextual Notes

Assumptions about friction, energy conservation, and the behavior of the system under different conditions are not fully resolved, leaving room for further exploration.

wolram
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If i had a driven flywheel with a hollow outer rim, and could rapidly fill it with water while in motion, would i gain any energy?
 
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If you will rapidly fiill it with water while moving, in the first moment water would be still, than friction would cause the water to start moving but the friction would also slow down the flywheel. Means no. You won't gain any energy.
 
Actually, you would lose energy. The momentum would remain the same, and the net energy would decrease. As Tominator said, the flywheel would slow down as the water accelerated, and the final state would be significantly slower than the initial state.
 
Assume that the flywheel has water in it but it's walls are frictionless so the water isn't moving. Then assume vanes in the flywheel are deployed to accelerate the water up to flywheel speed. Ignoring losses to heat, it's a closed system, so energy and momentum are preserved.
 
Ah, thanks every one.
 
Jeff Reid said:
Assume that the flywheel has water in it but it's walls are frictionless so the water isn't moving. Then assume vanes in the flywheel are deployed to accelerate the water up to flywheel speed. Ignoring losses to heat, it's a closed system, so energy and momentum are preserved.

True. I was thinking of kinetic energy, which would decrease (and heat would increase).
 

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