题目内容
如图所示,从倾角为45
的固定斜面B点正上方,距B点的高度为h的A点处,静止释放一个质量为m的弹性小球,落在B点和斜面碰撞,碰撞后速度大小不变,方向变为水平,经过一段时间小球落在斜面上C点。空气阻力不计,重力加速度为g。则( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132248293196.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241322483409789.png)
A.小球落到C点时重力的瞬时功率为mg![]() |
B.小球从B点运动到C点的时间为![]() |
C.小球从B点运动到C点的时间为![]() |
D.B点和C点间的高度差为4h |
CD
A→B:
解得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132248527647.png)
在B点:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132248589743.png)
B→C:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241322486361348.png)
解得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132248667910.png)
所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132248761954.png)
可见AB错误,CD正确。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132248496833.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132248527647.png)
在B点:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132248589743.png)
B→C:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241322486361348.png)
解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132248667910.png)
所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132248698855.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132248730790.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132248761954.png)
可见AB错误,CD正确。
![](http://thumb2018.1010pic.com/images/loading.gif)
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