[填空题]
A hollow cylinder (hoop) is rolling on a horizontal surface lt5m7c:t u*u 0 3vwdbuat stwz3q*sxn3 ,il6 o :ocpeed 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