题目内容
物体沿直线运动,经过A、B两点的速度分别为Va和Vb,经过A和B的中点速度为Vc,且Vc=(Va+Vb)/2;已知物体在AC段做加速度为
的匀加速直运动,在CB段做加速度为
的匀加速直线运动,则( )
A、
=
B、
>
C、
<
D、不能确定。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130957542254.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130957573269.png)
A、
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130957542254.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130957573269.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130957542254.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130957573269.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130957542254.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130957573269.png)
C
借助v--t图像假
=
设则Vc=(Va+Vb)/2,因为图线与t轴所围面积表示位移,C为中点所以后半段图线斜率应该小些,即
>![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130957573269.png)
所以选B
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130957542254.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130957573269.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130957542254.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130957573269.png)
所以选B
![](http://thumb2018.1010pic.com/images/loading.gif)
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