题目内容
汽车以v0=10m/s的速度在水平路面上匀速运动,刹车2s后它的速度降为6m/s。求:
(1)刹车过程中的加速度;
(2)刹车后经多长时间汽车停下;
(3)汽车从刹车开始到停下所发生的位移
(1)刹车过程中的加速度;
(2)刹车后经多长时间汽车停下;
(3)汽车从刹车开始到停下所发生的位移
(1)
(2)
(3)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160046854655.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160046557630.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160046713414.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160046854655.png)
试题分析:(1)由运动学公式可得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160047025564.png)
将数据代入①式可解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160046557630.png)
(2)汽车停车所需时间t,由运动学公式可得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160047322553.png)
由③式可解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160046713414.png)
(3)汽车从刹车到停下所通过的位移是s,则:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160047774650.png)
由⑤式可解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160046854655.png)
点评:在分析汽车刹车问题时,不能一味的带公式,需要先判断汽车静止所用的时间,跟题目中时间对比,
![](http://thumb2018.1010pic.com/images/loading.gif)
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