题目内容
(10分)如图8所示,光滑坡道顶端距水平面高度为h,质量为m的小物块A从坡道顶端由静止滑下,进入水平面上的滑道时无机械能损失,为使A制动,将轻弹簧的一端固定在水平滑道延长线M处的墙上,另一端恰位于滑道的末端O点.已知在OM段,物块A与水平面间的动摩擦因数均为μ,其余各处的摩擦不计,重力加速度为g,求:
(1)物块滑到O点时的速度大小;
(2)弹簧为最大压缩量d时的弹性势能(设弹簧处于原长时弹性势能为零)
(3)若物块A能够被弹回到坡道上,则它能够上升的最大高度是多少?![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241218378324123.jpg)
(1)物块滑到O点时的速度大小;
(2)弹簧为最大压缩量d时的弹性势能(设弹簧处于原长时弹性势能为零)
(3)若物块A能够被弹回到坡道上,则它能够上升的最大高度是多少?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241218378324123.jpg)
(1)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837863444.gif)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837878599.gif)
(3)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837894465.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837863444.gif)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837878599.gif)
(3)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837894465.gif)
(1)由机械能守恒定律得
,解得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837863444.gif)
(2)在水平滑道上物块A克服摩擦力所做的功为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837941491.gif)
由能量守恒定律得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837956679.gif)
以上各式联立求解得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837878599.gif)
(3)物块A被弹回的过程中,克服摩擦力所做的功仍为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837941491.gif)
由能量守恒定律得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121838190616.gif)
解得物块A能够上升的最大高度为:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837894465.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837910555.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837863444.gif)
(2)在水平滑道上物块A克服摩擦力所做的功为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837941491.gif)
由能量守恒定律得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837956679.gif)
以上各式联立求解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837878599.gif)
(3)物块A被弹回的过程中,克服摩擦力所做的功仍为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837941491.gif)
由能量守恒定律得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121838190616.gif)
解得物块A能够上升的最大高度为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121837894465.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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