题目内容
以10m/s的速度匀速行驶的汽车,刹车后做匀减速直线运动,若汽车刹车后第2s内的位移为6.25m(刹车时间超过2s),则汽车刹车后6s内通过的位移是多大?
20 m
设汽车刹车时的加速度为a,则有:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114153049895.gif)
其中
="10" m/s,
="6.25" m,
="2" s,
="1" s,代入数据解得a=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114153127418.gif)
汽车速度减到零所用时间
4 s<6s,即汽车在4s末停止后,剩余的2s处于静止状态,所以刹车后6s内的位移与4s内的位移相同,即:
20 m。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114153049895.gif)
其中
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114153064204.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114153080342.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114153095201.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114153111199.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114153127418.gif)
汽车速度减到零所用时间
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114153142479.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114153142568.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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