[问答题]
A wheel of mass M has radius R. It is standing verticallgvm:y i,.-im mkucw,2y on the floor, andzoi (:czgrw1gasee7 , x,c(z .v3w6,m*kbuo j we want to exert a horizontal force F at its axle g(71. ga6wi,,o (um k:rv w3cbezsez*,jzcox so that it will climb a step against which it rests (Fig. 8–55). The step has height h, where h
