Spin reversal of a rattleback with viscous friction
  Effective equation of motion of a rattleback is obtained from the basic equation of motion with viscous friction depending on slip velocity. This effective equation of motion is used to estimate the number of spin reversals and the rattleback shape that causes the maximum number of spin reversals. These estimates are compared with numerical simulations based on the basic equation of motion. 
Hiroshi Takano
physics.class-ph