Image:Equatorial bulge model.png

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[edit] Summary

Description:
Drawing of an apparatus for demonstrating the physics of the equatorial bulge of a rotating planet. The oval is a spring-metal band. The elasticity of the spring-metal tends to pull the band towards a circular shape. When the device is spun up, the torque increases the energy. Half the energy goes into increasing the rotational energy of the spring-metal band, the other half goes into potential energy of the elastic deformation of the band.

When the device is no longer driven, and energy is dissipating due to friction, the spring metal band models the equilibrium that determines the shape of the Earth. Friction dissipates kinetic energy. At the same time the kinetic energy is to some extent replenished by the contraction of the spring-metal band. Due to the contraction, the angular velocity decreases less than would be the case with a solid object that is losing energy through friction.

If the spring-metal band spins up slowly, and spins down slowly, then at each point in time the amount of potential energy is equal to the amount of rotational kinetic energy.

Created:
22 September 2006

Author: Cleonis

Authorship remark:
The drawing itself is own work, the design of the device is copied. In the book the life and science of Léon Foucault by William Tobin, a drawing of this device is in chapter 9.

[edit] Licensing

I, the copyright holder of this work, hereby publish it under the following licenses:

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. Subject to disclaimers.

This file is licensed under the Creative Commons Attribution-ShareAlike license versions 2.5, 2.0, and 1.0.

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File history

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	Date/Time	Dimensions	User	Comment
current	20:55, 22 September 2006	256×176 (6 KB)	Cleonis (Talk \| contribs)	(Follow-up with version that does not need resizing. )
	20:52, 22 September 2006	1,024×704 (12 KB)	Cleonis (Talk \| contribs)	('''Description:'''<br> Drawing of an apparatus for demontrating the physics of the equatorial bulge of a rotating planet. The oval is a spring-metal band. The elasticity of the spring-metal band pulls pulls toward a circular shape. When the device is spun)