[问答题]
A wheel of mass M has/3 odgt4 +m c0svmhy5n radius R. It is standing vertically on the/kcjcunvk( i05o) ib 5k1d iq* floor, and we want to exert a horizontal force F at its axle so that it will climb a step against which it rests (Fig. 8–55). The step has height h, wherek/5ijc1 nv)qoubc(5d kk0i*i h