题目内容
如图所示,质量为m的物体用细绳车牵引着在水平光滑面上做匀速圆周运动,当拉力为F时,转动半径为R,当外力增大到8F时,物体仍然做匀速圆周运动,其转动半径为
.在此过程中,外力对物体所做的功是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241139362051689.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113936174244.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241139362051689.jpg)
A.![]() | B.![]() |
C.![]() | D.4FR |
A
由于F=
,8F=
,由动能定理
W=
mv22-
mv12=
FR,A正确.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113936268425.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113936283473.gif)
W=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113936299225.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113936299225.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824113936221228.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目
题目内容
A.![]() | B.![]() |
C.![]() | D.4FR |