题目内容
质量为m的汽车在平直公路上从速度大小为V0开始加速运动,前进了s的距离时速度达到最大值Vm,设在此运动过程中汽车发动机的功率恒为P。则汽车所受的阻力(假设恒定)为 ;此过程发动机做的功为 ;此过程经历的时间为 。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824202148158512.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242021489231136.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242021499681107.png)
试题分析:当牵引力等于阻力时速度最大,此时有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824202151044776.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242021521051173.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242021489231136.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824202154227585.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242021499681107.png)
点评:本题难度较小,处理此类问题要先弄清是恒定功率启动还是匀加速启动
![](http://thumb2018.1010pic.com/images/loading.gif)
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