[填空题]
A hollow cylinder (hoop) is rolling on a horizontal surface kv61,o-wk7+* mxmkayw to,qu at t,;y hfqvlr3 f-+v9 ,icl(s8hnpf i3vspeed v=3.3 $m/s$ when it reaches a 15 $^{\circ} $ incline. (a) How far up the incline will it go? $\approx$ m (round to one decimal place) (b) How long will it be on the incline before it arrives back at the bottom? s