[单选题]
A roller coaster starts at a point 30 m ab 84vy (j mnoga1c vtcyo7k++)xove the bottom n xd c 0m:ntdlzrmr25p0 e6qf/69j xu4of a dip with a speed of 25 m/s 0rf:cner5xx9z06dm 42 tp6/jqdmu nl (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip? 
A. 14 m/s
B. 16 m/s
C. 18 m/s
D. 20 m/s
参考答案: C
本题详细解析:
暂无
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