题目内容
如图16-7-8所示,两根相距l的竖直平行金属导轨位于匀强磁场中,磁感应强度为B,导轨电阻不计,另两根与光滑导轨接触的金属杆质量均为m,电阻均为R.若要使cd杆恰好平衡,且静止不动,则ab杆应向____________做____________运动,ab杆运动速度的大小是____________,对ab杆所加外力的大小为_______________.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241210103782070.jpg)
图16-7-8
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241210103782070.jpg)
图16-7-8
上 匀速
2mg
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121010394527.gif)
ab杆向上匀速运动对cd有:mg=BIL=
,所以v=
由整体得F=2mg.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121010410485.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121010394527.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目