题目内容
一个质量为
的物体以某一速度从固定斜面底端冲上倾角
=30°的斜面。已知该物体做匀减速运动的加速度为
,在斜面上上升的最大高度为
,则此过程中( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134654883337.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134654915283.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134655024477.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134655071313.png)
A.物体的动能增加![]() | B.物体的重力做功![]() |
C.物体的机械能损失了![]() | D.物体所受摩擦力做功![]() |
C
物体在沿斜面上升的过程中,受到重力沿斜面向下的分力与沿斜面向下的摩擦力,根据牛顿第二定律得到
,Ff=
,物体在上升h的过程中,重力做的功为
,B错;摩擦力做的功为
,C对,D错;由动能定理得
,得到
,即物体的动能减少
,A错。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241346555701080.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134655648537.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134655726720.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241346557881027.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134655882962.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134655991824.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134656147663.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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