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1995年高考物理试题第30题是一道难题。题目是这样的: 如图所示,一排人站在沿x轴的水平轨道旁,原点0两侧的人的序号都记为n(n=1、2、3、……)。每人只有一个沙袋,x>0一侧的每个沙袋质量为m=14千克,x<0一侧的每个沙袋质量为m′=10千克,一质量为M=48千克的小车以某初速度从原点出发向正x方向滑行,不计轨道阻力。当车每经过一人身旁时,此人就把沙袋以水平速度u朝与车速相反的方向沿车面扔到车上,u的大小等于扔此袋之间的瞬间车速大小的2n倍(n是此人的序号数)。
The 30th issue of the 1995 physics examination entrance exam was a difficult problem. The topic is this: As shown in the figure, a row of people is standing next to the horizontal track along the x-axis, and the numbers of people on both sides of the origin 0 are recorded as n (n=1, 2, 3,...). Each person has only one sandbag, the mass of each sandbag on the x>0 side is m=14kg, the mass of each sandbag on the x<0 side is m’=10kg, and the mass of one trolley is M=48kg. The initial speed starts from the origin and slides in the positive x direction, excluding the track resistance. Whenever the car passes by a person, the person throws the sandbag along the surface of the car at a horizontal speed u in the opposite direction to the speed of the car. The size of the u is equal to 2n times the instantaneous speed between the bags. Is the serial number of this person).