- For the fictional / theorized future animal, see Rattleback (rodent).
Also known as a "wobblestone", "celtic stone" or simply "celt", the rattleback is a semi-ellipsoidal object that reverses its spin direction. The rattleback seems to violate conservation of angular momentum.
It is somewhat controversial as to what causes this apparent violation of conservation of angular momentum. One theory is that its the result of a non-zero product of inertia.
Video and more information available here.
"Torque of the Devil" http://www.physics.brown.edu/physics/demopages/Demo/solids/demos/torque.html http://www.4physics.com:8080/phy_demo/rattleback.htm
Physics demo instructions http://www.sfu.ca/physics/ugrad/courses/teaching_resources/demoindex/mechanics/mech1q/celt.html http://www.tam.uiuc.edu/toys/celt/
Sources of Rattlebacks:
http://www.physlink.com//estore/cart/BizzaroSwirls.cfm
http://www.grand-illusions.com/toyshop/russian_rattleback/
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