题目内容
用水平力拉一物体在水平地面上从静止开始做匀加速运动,到
秒末撤去拉力F,物体做匀减速运动,到
秒末静止。其速度图象如图所示,且
。若拉力F做的功为W,平均功率为P;物体在加速和减速过程中克服摩擦阻力做的功分别为
和
,它们的平均功率分别为
和
,则下列选项正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241138224791878.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822339199.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822370201.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822386281.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822401344.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822417347.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822448202.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822464218.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241138224791878.jpg)
A.![]() | B.![]() |
C.![]() | D.![]() |
AD
物体在拉力作用下运动的过程中所有力做功的和为零,
,A正确。
与
内的位移不等,所以
,B错。因
与
内的平均速度相等,
,D正确。
与
时间不等,故
,C错误。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822557525.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822573253.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822589259.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822604432.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822573253.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822589259.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822651584.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822573253.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822589259.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113822698334.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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