"Walking" Along a Free Rotating Bicycle Wheel (Round and Round)
  We describe the kinematics, dynamics and also some energetic issues related to the Marta mouse motion when she walks on top of a horizontal bicycle wheel, which is free to rotate like a merry-to-go round, as presented recently by Paul Hewitt in the Figuring Physics section of this magazine. 
Julio Guemez, Manuel Fiolhais
physics.ed-ph physics.pop-ph