有一道中学物理习题: 一列火车正午时离开火车站,以48千米/小时的速度向东行驶。下午两点时,另一列火车以40千米/小时的速度离开车站向南行驶,将两列火车间的距离d表示为时间t的函数,t从第二列火车离开车站时刻算起。解答这一问题,可以车站为坐标原点,向东为x轴正向,向南为y轴正向,如图1所示,则向东火车的位置由x=96+48t给出,向南火车的位置由y=40t给出,两车间的距离为 d=8(61t~2+144t+144)~(1/2). (1)至此该题似乎已解答结束了,但如果我们问:t取何值,两列火车处于同一位置,即d=0?由方程(1)令d=0可得到t的复数 There is a middle school physics problem: A train leaves the train station at noon and travels east at a speed of 48 km/h. At 2 o’clock in the afternoon, another train left the station at a speed of 40 km/h and travelled south. The distance d between the two trains is represented as a function of time t, and t counts from the moment the second train leaves the station. To answer this question, the station can be the origin of the coordinates, with the positive x-axis to the east and the positive y-axis to the south. As shown in Figure 1, the position of the east train is given by x=96+48t. The position of the train is given by y=40t. The distance between the two workshops is d=8(61t~2+144t+144)~(1/2). (1) The question seems to have been answered and ended, but if we ask :t What is the value of the two trains in the same position, that is, d = 0? Let d=0 from equation (1) to obtain the complex number of t.