题目内容
汽车在水平路面上从静止开始做匀加速直线运动,t1末关闭发动机,做匀减速直线运动,t2末静止,其v-t图像如图所示,图中α<β,若汽车牵引力做功为W,牵引力平均功率为P;汽车加速和减速过程中克服摩擦力做功分别为W1和W2,摩擦力平均功率分别为P1和P2,则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241957286202072.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241957286202072.jpg)
A.W=W1+W2 | B.W1>W2 | C.P=P1 | D.P1=P2 |
AD
试题分析:由已知
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241957289631000.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824195730024775.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824195730897851.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241957312871010.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241957322541921.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824195733222754.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824195734142410.png)
点评:本题难度较小,从运动图像中,把整个运动分成两个阶段,对每一个阶段进行受力分析和做功分析,注意阻力做功与路径无关,图线的面积表示位移大小
![](http://thumb2018.1010pic.com/images/loading.gif)
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