题目内容
同一恒力按同样方式施于物体上,使它分别沿着粗糙水平地面和光滑水平面移动相同一段距离时,恒力的功和平均功率分别为
、
和
、
,则二者的关系( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172233094420.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172233312315.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172233515448.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172233702348.png)
A.![]() ![]() | B.![]() ![]() |
C.![]() ![]() | D.![]() ![]() |
B
试题分析:根据公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172236323544.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172234872536.png)
设在粗糙水平面上运动的加速度为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172237072315.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172237274291.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172237508344.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172237820327.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172238086441.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172238351625.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172238600426.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172238897595.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824172239146442.png)
故选B
点评:同样的恒力作用在物体上,通过的位移相等,则恒力做功相等,通过比较运动的时间比较平均功率.
![](http://thumb2018.1010pic.com/images/loading.gif)
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A.![]() ![]() | B.![]() ![]() |
C.![]() ![]() | D.![]() ![]() |