题目内容
在平直的公路上,汽车由静止开始做匀加速运动,当速度达到一定值后立即关闭发动机,汽车继续滑行直到停止。这辆汽车
图象如图所示,设在汽车行驶的整个过程中,汽车的牵引力和汽车所受的阻力都是恒定的,汽车牵引力大小为F,阻力大小为f。在汽车行驶的整个过程中,牵引力做功为W1,克服阻力做功为W2,则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241238478952749.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123847770362.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241238478952749.png)
A.F∶f =3∶1 | B.F∶f =2∶1 | C.W1∶W2=1∶1 | D.W1∶W2=3∶2 |
AC
本题考查速度时间图像。由图像知,关闭发动机前加速度
,关闭发动机后
,由牛顿第二定律,
,可得
,A对;由动能定理,
,所以
,C对;选AC。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123847926642.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123847941712.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123847957743.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123847988531.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123848144599.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123848160613.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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