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Rattleback.
Rattleback Physics
56,361 views
casewm
99 subscribers
Published on Aug 23, 2013
A presentation of the physics of the rattleback at an introductory level.
PS: If the initial rotation is in the opposite direction the rattleback will rock side to side about the long axis. Since the moment of inertia about this axis is much less that that about the short axis the rattleback will not reverse. In addition, from this argument you can see how to modify the rattleback so it will reverse in both directions.
56,361 views
casewm
99 subscribers
Published on Aug 23, 2013
A presentation of the physics of the rattleback at an introductory level.
PS: If the initial rotation is in the opposite direction the rattleback will rock side to side about the long axis. Since the moment of inertia about this axis is much less that that about the short axis the rattleback will not reverse. In addition, from this argument you can see how to modify the rattleback so it will reverse in both directions.
From Wikipedia, https://en.m.wikipedia.org/wiki/Rattleback :
Rattleback
A rattleback is a semi-ellipsoidal top which will rotate on its axis in a preferred direction. If spun in the opposite direction, it becomes unstable, "rattles" to a stop and reverses its spin to the preferred direction.
This spin-reversal appears to violate the law of the conservation of angular momentum. Moreover, for most rattlebacks the motion will happen when the rattleback is spun in one direction, but not when spun in the other. Some exceptional rattlebacks will reverse when spun in either direction.[1] This makes the rattleback a physical curiosity that has excited human imagination since prehistoric times.[2]
A rattleback may also be known as a "anagyre", " (rebellious) celt", "Celtic stone", "druid stone", "rattlerock", "Robinson Reverser", "spin bar", "wobble stone" (or "wobblestone" ) and by product names including "ARK", "Bizzaro Swirl", "Space Pet" and "Space Toy".
[...]
A rattleback is a semi-ellipsoidal top which will rotate on its axis in a preferred direction. If spun in the opposite direction, it becomes unstable, "rattles" to a stop and reverses its spin to the preferred direction.
This spin-reversal appears to violate the law of the conservation of angular momentum. Moreover, for most rattlebacks the motion will happen when the rattleback is spun in one direction, but not when spun in the other. Some exceptional rattlebacks will reverse when spun in either direction.[1] This makes the rattleback a physical curiosity that has excited human imagination since prehistoric times.[2]
A rattleback may also be known as a "anagyre", " (rebellious) celt", "Celtic stone", "druid stone", "rattlerock", "Robinson Reverser", "spin bar", "wobble stone" (or "wobblestone" ) and by product names including "ARK", "Bizzaro Swirl", "Space Pet" and "Space Toy".
[...]