题目内容
如图,倾角为
的斜面体放在粗糙的水平面上,质量为m的物体A与一劲度系数为k的轻弹簧相连.现用拉力F沿斜面向上拉弹簧,使物体A在光滑斜面上匀速上滑,上滑的高度为h,斜面体始终处于静止状态。在这一过程中
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250015247834505.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001524752314.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250015247834505.jpg)
A.弹簧的伸长量为![]() |
B.拉力F做的功为![]() |
C.物体A 的机械能增加mgh |
D.斜面体受地面的静摩擦力大小等于Fcos![]() |
CD
试题分析:物体A在斜面上匀速运动,弹簧的弹力等于F,弹簧的伸长量为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001524861429.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001524892168.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001524908898.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001524923593.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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