[问答题]
A wheel of mass M has radius R. It is standing vwcf 1y3mh6 o+jeri cuqu )3pykis6*l)b )tically on the floor, and we want to exert a horizontal force F at its axle so that it wi) uiqu)sl*p)b 6 yc3kill climb a step against which it rests (Fig. 8–55). The step has height h, where h