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Old 07-09-2010, 10:24 AM   #127 (permalink)
Patrick
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Quote:
Originally Posted by Christ View Post
You might extract more energy from a flywheel if you can change it's angular momentum.

In other words, if you start with a small diameter flywheel, and make it expand as it speeds up, then extract it's energy after it's at maximum speed/diameter, you get more angular momentum. You can put less energy into it and get more out than you normally would. It just brings the energy input/output closer to equilibrium, is all.

You'd have to make it so that it only contracts once the usable energy is used up, though, so as not to lose the momentum developed prematurely.

Does this make sense? Just something I thought of.
Umm, no. You will get the same amount of energy out that you put in, less any friction losses. Angular momentum is conserved.

"The conservation of angular momentum explains the angular acceleration of an ice skater as she brings her arms and legs close to the vertical axis of rotation. By bringing part of mass of her body closer to the axis she decreases her body's moment of inertia. Because angular momentum is constant in the absence of external torques, the angular velocity (rotational speed) of the skater has to increase."

Angular momentum - Wikipedia, the free encyclopedia

You might lose even more than a regular flywheel due friction in the mechanism.
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