题目内容
火车以速度
匀速行驶,司机发现前方同轨道上相距S处有另一列火车沿同方向以速度
(对地、且
)做匀速运动,司机立即以加速度
紧急刹车,要使两车不相撞,
应满足什么条件?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122324669200.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122324685205.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122324685254.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122324701192.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122324701192.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122324732554.gif)
解:设两车恰好相撞,所用时间为t,此时两车速度相等
v1-at=v2
此时位移关系如图
S+S2=S1
S1=v1t-![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122324747404.gif)
S2=v2 t
由以上计算式可得
a=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122324763501.gif)
所以要使两车不相撞![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122324732554.gif)
【标签】直线运动追及和相遇问题
v1-at=v2
此时位移关系如图
S+S2=S1
S1=v1t-
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122324747404.gif)
S2=v2 t
由以上计算式可得
a=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122324763501.gif)
所以要使两车不相撞
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122324732554.gif)
【标签】直线运动追及和相遇问题
![](http://thumb2018.1010pic.com/images/loading.gif)
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