加速t1，加速度4减速t2，加速度54*t1=85, t1=21.25s5t2=85, t2=17s总时间t1+t2=38.25s
因为V = at所以t = V/aT = t1 + t2t1 = V/a = 85/4 = 21.25st2 = V/a = 85/5 = 17s所以 T = 21.25 + 17 = 38.25s
