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1984年高考物理第五题其题目主要内容如图1所示(题从略)。解答此题关键是如何对绳端速度正确进行分解,由于较多学生对绳端运动情况缺乏正确认识,把车的水平速度看作绳速度的一个分速度,因而出现如图2所示错误分解。为了让学生对绳端速度分解有一个正确认识,对此问题除用分析法说明外,还可用下述实验法说明。实验制作方法:用一个轻盈的硬质纸筒(如较长的酒精温度计装筒),在纸筒一端固定一块金属薄片,薄片上打一小孔做轴孔,然后将绳(绳穿过两端开口的纸
In 1984, the fifth item of Physics in the National College Entrance Examination was the main content of the title as shown in Figure 1 (the subject omitted). The key to solving this question is how to correctly decompose the speed of the rope end. Because many students lack a correct understanding of the rope end movement, the horizontal speed of the car is regarded as a sub-speed of the rope speed, and thus an error decomposition appears as shown in FIG. 2 . . In order to allow students to have a correct understanding of the rope speed decomposition, this problem can be explained by the following experimental method, in addition to the analytical method. Experimental method: use a light and rigid paper tube (such as a long alcohol thermometer tube), fix a piece of metal sheet on the end of the paper tube, make a small hole in the film to make the shaft hole, and then pass the rope (through the rope Open end paper