题目内容
质量为
的物体,在
、
、
三个共点力的作用下处于平衡状态,保持
、
不变,仅将
的方向改变90°(大小不变)后,物体可能做
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824181017914337.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824181018179333.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824181018460353.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824181018725366.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824181018179333.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824181018460353.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824181018725366.png)
A.加速度大小为![]() |
B.加速度大小为![]() |
C.加速度大小为![]() |
D.类平抛运动 |
BCD
试题分析:改变后在
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824181018179333.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824181018460353.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824181018725366.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824181018725366.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824181021408485.png)
若撤出前物体处于静止状态,则改变后物体做加速度大小为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824181019895628.png)
若改变前的运动方向和改变后的合力方向不共线,则做加速度大小为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824181019895628.png)
若物体是在空中运动,则可能做类平抛运动,D正确
故选BCD
点评:关键是能分析改变前物体的运动状态,结合曲线运动条件分析
![](http://thumb2018.1010pic.com/images/loading.gif)
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