题目内容
在一平板上放一重为G=9.8N的物体,当振幅为2cm时,平板做简谐运动的最大加速度为a=3.2
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120355510997.gif)
(1)平板在竖直方向做简谐运动,位移的大小为2cm时,物体作用在板上的压力多大?为了使物体不与板脱离,平板的振幅不能超过多大?
(2)设物体跟平板间的最大静摩擦力为3.2N,平板在水平方向做简谐振动,振幅满足什么条件,物体才不致于在板上发生滑动?
(1)13.0N ,0.06cm(2)2.0cm
(1)回复力F=kA=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120355556979.gif)
∴ k=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241203555721025.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241203555721109.gif)
设向上为正,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120355588942.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241203556031094.gif)
∴
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241203556191076.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120355634948.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241203556501070.gif)
∴
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241203556661075.gif)
当平板在平衡位置上方时,物体平板压力小于重力,当N=0时的振幅
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120355681960.gif)
-G=-
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120355697985.gif)
∴
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241203558841293.gif)
(2)回复力F=kA≤
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120355900947.gif)
∴ A≤
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241203559151114.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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