题目内容
、为了安全,汽车过桥的速度不能太大。一辆汽车由静止出发做匀加速直线运动,用10s时间通过一座长120m的桥,过桥后的速度是14m/s。请计算:
(1)它刚开上桥头时的速度有多大?
(2)桥头与出发点的距离多远?
(1)它刚开上桥头时的速度有多大?
(2)桥头与出发点的距离多远?
(1)10m/s(2)125m
试题分析:(1)设汽车刚开上桥头的速度为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155737158298.png)
则有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155737454678.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155737626185.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155737797663.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155737875892.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155738062541.png)
(2)汽车的加速度
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155738296595.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155738437772.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155738562622.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155737626185.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241557389051236.png)
点评:解决本题的关键掌握匀变速直线运动的速度位移公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824155739014648.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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