[填空题]
A hollow cylinder (hoop) is rolling on a hootgr*qi(mr9blbc uj1 , 9xn0ae :q(l; rizontal surface at el l0fx kqlsml fnf)5) a9d3,4speed 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