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一、穷举法当某个问题有几种可能性,而一时难以判定时,可以把各种可能情况全部列出,再逐一分析,找出与已知条件或要求解的结论相符合的情况,这种方法称为穷举法。有些物理问题必须用穷举法,才能求解。例1.A 与 B 滑块在一光滑的水平直轨道上发生正碰,用闪频照相在 t_0=0,t_1=Δt、t_2=2Δt、t_3=3Δt 各时刻闪光四次,摄得如图1所示照片,照片中出现 A的四个像和 B 的两个像。已知在这四次闪光的瞬间 B的运动未超出照片所示范围,试判断两滑块发生碰撞的时刻和地点。解:四次闪光却只有 B 的两个像,这说明 B 的四个像重叠成了两个像。重叠的情况有三种可能:(1)两个像都是两重的重叠像。(2)右边的像是三重像,左边
First, the exhaustive method When there are several possibilities for a problem, and when it is difficult to determine, you can list all possible situations and analyze them one by one to find out the conditions that are consistent with the known conditions or the conclusions of the solution. This method is called exhaustive. Some physical problems must be exhausted to solve them. Example 1. The A and B sliders collide in a smooth horizontal straight track, and they are flashed four times with t_0=0, t_1=Δt, t_2=2Δt, and t_3=3Δt at each moment. 1 Photographs of the four images of A and two images of B appear in the photo. It is known that during the four flashes, the movement of B does not exceed the range shown in the photo. Try to determine the time and place where the two sliders collided. Solution: There are only two images of B in the four flashes. This shows that the four images of B overlap into two images. There are three possibilities for overlapping: (1) Both images are double overlapping images. (2) The image on the right is a triple image, left