题目内容
一辆质量为M的超重车,行驶上半径为R的圆弧形拱桥顶点,已知此处桥面能承受的最大压力只是车重的
倍,要使车能安全沿桥面行驶,求在此处车的速度应在什么范围内?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124419785385.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124419879807.png)
当汽车在拱桥顶端运动时,运动的向心力完全由重力充当时:
,解得
,若超过这个速度,汽车将做平抛运动,故![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124419941534.png)
当汽车对拱桥的压力正好是车重的
倍时,
,解得
,若小于这个速度,汽车对拱桥的压力大于车重的
倍,
所以![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124419879807.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124419910718.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124419926507.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124419941534.png)
当汽车对拱桥的压力正好是车重的
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124419785385.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124419988968.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124420035645.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124419785385.png)
所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124419879807.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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