Rattleback: Difference between revisions

Revision as of 07:37, 10 December 2006

Revision as of 10:55, 10 December 2006

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[[Image:Celt_with_gemstone_turtles-01.jpg|thumb|300px|Carved wooden rattleback]]

A '''rattleback''', also known as a "celt," "Celtic stone" or "wobblestone," and by the product names "ARK," "RATTLEBACKS" and "Space Pets," is a semi-ellipsoidal [[top]] which will spin on its axis in a preferred direction. But, if spun in the opposite direction, it becomes unstable, "rattles," stops and reverses its spin to the preferred direction.

This spin-reversal motion seems, at first sight, to violate the [[angular momentum|angular-momentum]] conservation law of physics. Moreover, for most rattlebacks, the motion will happen when the rattleback is spun in one direction, but not when spun in the other. These two peculiarities make the rattleback a physical curiosity that has excited human imagination since prehistorical times.

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While rattleback [[Artifact (archaeology)|artifact]]s are described as stone with various measurements, most which are sold currently as novelty puzzles and toys are described as plastic with measurements of 3.75-inches length x 0.75-inches width x 0.4375-inches height. Carved wooden rattlebacks are described with a measurement of 6-inches length. One plastic rattleback made and sold by Charles W. Sherburne is described with a measurement of 12-inches length. Glass rattlebacks are described as being tested with unreported measurements. Larger rattlebacks, and those of other materials, aren't yet reported.

Two rattleback-design types of rattlebacks exist. The first enjoys an asymmetrical base where its rolling axis is skewed. The second enjoys a symmetrical base with off-set weighting at the ends of the rattleback.

==Physics==

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Rattlebacks have been misdescribed and misused as:

*A tool of [[Divinationdivination]]

*Influenced by [[Magic (paranormal)|magic]]