[领域] 弹簧 [来源] 参考书 [题目] A spring with spring constant k=200N/m is suspended vertically with its upper ebd fixed to the ceiling and its lower end at position y=0. A block of weight=20N is attached to the lower end, held still a moment, and then released. What are (a) the kinetic energy K,(b)the change(from the initial value)in the gravitational potential energy ΔUg,and (c)the change in elastic potential energyΔUe of the spring-block system when the block is at y=-5cm? What are (d)K,(e)ΔUg,and (f)ΔUe when y=-10cm? 题目还有问-15cm和-20cm [瓶颈] 题目有点看不懂 在挂物体的时候 事先让它呈平衡的状态嘛? 因为这个题目一直让我联想到简谐运动 始终一直搞混 麻烦高手解答一下 另外 F=KX 20=200X X不是等於0.1m吗? 怎麽会有到-15和-20cm的时候呢? --

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