题目内容
一辆汽车沿直线运动,先以15m/s的速度驶完全程的四分之三,剩下的路程以20m/s的速度行驶,则汽车从开始到驶完全程的平均速度大小为( )
A.16m/s | B.16.3m/s | C.17.5m/s | D.18.8m/s |
A
试题分析:设全程的位移大小为4x,根据
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144709441477.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144709535679.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144709644573.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144709706545.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144709753749.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144709862628.png)
点评:此类型的题目属于常规题,关键抓住平均速度的定义列式.
![](http://thumb2018.1010pic.com/images/loading.gif)
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题目内容
A.16m/s | B.16.3m/s | C.17.5m/s | D.18.8m/s |