[填空题]
A hollow cylinder (hoop)sf8rbv*i1 -5o *skc6 j0k fdxo is ro 6ai8a3w wjr++mb:so llling on a horizontal surface at speed 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