同学们，你坐过游乐场的“单轨滑车”或玩过“激流勇进”吗？当你从高处急剧下降时有什么感觉？是不是觉得心像悬（xuán）起来似的？为什么会有这种感觉呢？让我们来做个实验从中找出答案吧。一、实验材料：饮料罐一只、细绳一根、水。二、实验方法：在饮料罐侧面开几个光滑小 Classmates, did you sit in the playground “monorail” or played “rapids”? What do you feel when you drop sharply from a height? Is it like hanging like (xuán) up like? Why do you feel this way? Let's experiment and find the answer. First, the experimental material: a beverage can, a string, water. Second, the experimental method: in the beverage cans open a few smooth side