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初二学生学了“惯性、惯性的应用”这节后,完成课本上的“练习三”非常困难,许多学生根本就不会做。我在教学中总结出“三步法”,同时把“练习三”移到下一节“运动和力”讲完后布置给学生,取得了很好的效果。“三步法”的内容是: 第一步:物体原来的运动状态怎么样? 第二步;哪个物体受外力作用,改变了运动状态? 第三步:哪个物体没有受外力作用,仍保持原来的运动状态? 例1.如图所示,把纸片突然弹去,钢球掉进筒里,为什
After the second grade students learned about the “application of inertia and inertia”, it was very difficult to complete “exercise three” in textbooks. Many students would not do it at all. I summed up the “three-step method” in my teaching, and at the same time moved “Exercise 3” to the students in the next section “Sports and Force”, and achieved good results. The content of the “Three Steps Law” is: Step 1: What is the original state of movement of the object? Step 2: Which object is affected by an external force and changes the state of movement? Step 3: Which object is not affected by the external force and remains as it is What is the state of movement? Example 1. As shown in the picture, the sheet of paper suddenly flicked and the steel ball fell into the tube.