题目内容
如图所示,倾角为
的光滑斜面向左做匀加速运动时,质量为m的小球恰好与斜面保持静止,当小球与斜面的速度从v增加到2v的过程
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250022334871966.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002233362389.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250022334871966.png)
A.斜面对小球m做功![]() |
B.斜面对小球支持力的大小为![]() |
C.小球m受到的合外力大小为mg |
D.重力对小球m做功不为零 |
AC
试题分析:对小球进行受力分析,如图所示:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250022335343902.png)
根据几何关系有:tan45°=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002233550601.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002233565572.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002233581344.png)
WN+WG=
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002233596338.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002233596338.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002233628388.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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