题目内容
在平直公路上,汽车作初速为0的匀加速运动,当速度达到v后立即关闭发动机直到停止,v-t图象如图所示。设汽车的牵引力为F,摩擦力为f,且f大小不变。全过程中牵引力做功W1,克服摩擦力做功W2,则( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241508430262637.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241508430262637.png)
A.F:f=1:3 | B.F:f=4:1 |
C.W1:W2 =1:1 | D.W1:W2=l:3 |
BC
试题分析:AB、加速阶段
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150843167622.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150843292554.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150843401517.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150843526564.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150843619544.png)
CD、
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150843744584.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150843838743.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150843931528.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150843994596.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150844087998.png)
故选BC
点评:中等难度。注意加速阶段受牵引力和摩擦力,减速阶段只受摩擦力,摩擦力全程都做功。
![](http://thumb2018.1010pic.com/images/loading.gif)
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