dsin 0-dp=Josin 0-dp dMdt =mgrsin 0.di Josin 0.do=mgrsin 0.dt L+dL d= mgr dt Jw   L  L dL    dL  d dL  M dt  mgrsin  dt   dL  L sin  d  J sin  d   Jsin  d  mgrsin  dt   J mgr dt d   