初中教材物理第一册简单机械一章中，关于定滑轮作用的实验虽然简单，但却不容易做好。我在教学中采用两个自重、量程尽量相同的弹簧秤，按照图１进行实验，使学生看出挂在左边弹簧秤钩上的钩码，使弹簧秤的示数是多少，而跨过定滑轮，用手拉右边弹簧秤钩，这时弹簧秤示数与左? In the Simple Mechanics chapter of the Physical Education Booklet for junior middle school textbooks, the experiment on the function of the pulley is simple, but it is not easy to do well. In my teaching, I used two spring scales with the same weight and the same measuring range. According to Figure 1, the experiment was carried out to make students see the hook code on the hook on the left side of the spring scale, so that the number of spring scales is displayed, and the number of spring scales is used to cross the fixed pulley. Pull the spring balance on the right hand side. When is the spring scale displayed to the left?