题目内容
质量为m的物体静止在光滑水平面上,从t=0时刻开始受到水平力的作用力的大小F与时间t的关系如图所示,力的方向保持不变,则( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082420041262912167.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082420041262912167.png)
A.3to时刻的瞬时功率为15Fo2to/m |
B.3to时刻的瞬时功率为5Fo2to/m |
C.在t="0" 到3to这段时间内,水平力的平均功率为23Fo2to/4m |
D.在t="0" 到3to这段时间内,水平力的平均功率为25Fo2to/6m |
AD
试题分析:、在
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824200413690477.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824200414345602.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824200414891699.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824200415812515.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824200416810688.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824200417808969.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242004188541107.png)
根据动能定理得,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242004195401601.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242004206161196.png)
故选AD.
点评:解决本题的关键掌握瞬时功率的公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824200421443614.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824200422270603.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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