[填空题]
A city planner is working on tl xnbdl16 wy 84s*vni0he redesign of a hilly portion 9k (ls5)u9+ gmfgvptt7dtum0of a city. An important consideration is how steep the roads can be 9g9luf( tm+gk70 s muptdt)v 5so that even low-powered cars can get up the hills without slowing down. A particular small car, with a mass of 1100 kg , can accelerate on a level road from rest to 21$ \mathrm{~m} / \mathrm{s}(75 \mathrm{~km} / \mathrm{h})$ in 14.0 s . Using these data, calculate the maximum steepness of a hill. $^{\circ}$
