Librational motion of asymmetric rolling bodies and the role of friction   force
  We designed a very simple asymmetric rolling spool and we studied it experimentally, in the librational regime, by using a video camera and video analysis software. Comparison of experimental results and theoretical analysis allows addressing critical aspects related both to the characteristic of the oscillatory anharmonic motion of the system and to the role of friction forces in determining it. For that reasons the asymmetric rolling spool can be presented to undergraduate students as an interesting case study where to apply their physics knowledge to understand the behavior of real objects. 
P. Onorato, M. Malgieri, P. Mascheretti and A. De Ambrosis
physics.ed-ph