Rattleback: Difference between revisions

Revision as of 18:43, 15 May 2006

Revision as of 08:50, 14 July 2006

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Also known as a "wobblestone", "celtic stone" or simply "celt", the '''rattleback''' is a semi-[[ellipsoid]]al object that reverses its spin direction, when spun one way, but behaves normally if spun the other. Also if held up by one end then let go it begins to spin. The rattleback seems at first sight, to violate [[conservation of angular momentum]].

It is somewhat difficult to mathematically explain the causes of the '''rattlebacksrattleback's''' strange motion. One explanation is that its the result of a [http://www.autolev.com/WebSite/SampleProblemRattleback/Rattleback.html non-zero product of inertia]. Basically it is the broken symmetry in the object that makes it's motion so strange.

Rattlebacks were found by archeologists investigating ancient Celtic and Egyptian sites, and some old Celtic axes demonstrate properties similar to rattlebacks.