题目内容
如图所示,力F大小相等,A、B、C、D 物体运动的位移s也相同,其中A、C图接触面光滑,B、D图接触面粗糙,哪种情况F做功最小![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241901545662498.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241901545662498.png)
D
试题分析:A选项中,拉力做功为:W=FS
B选项中,拉力做功为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190154800426.png)
C选项中,拉力做功为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190154800426.png)
D选项中,拉力做功为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824190155331377.png)
故D图中拉力F做功最少;
故选D.
点评:本题涉及恒力做功的求法,拉力F做功取决与力的大小、位移的大小和力与位移夹角的余弦三者的乘积,与是否有其他力做功无关.
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目
题目内容