题目内容
如图所示,通电导体棒AC静止于水平导轨上,棒的质量为m长为L,通过的电流强度为I,匀强磁场的磁感强度B的方向与导轨平面成θ角,求导轨受到AC棒的压力和摩擦力各为多大?![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241504196673800.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241504196673800.png)
mg-BIlcosθ,BIlsinθ
试题分析:导体棒AC静止于水平导轨上,受到重力、安培力、导轨的支持力和静摩擦力.导体棒与磁场方向垂直,安培力大小FA=BIl,根据左手定则判断安培力方向,根据平衡条件求解导轨对导体棒的支持力和摩擦力,再由牛顿第三定律求解导轨受到AC棒的压力和摩擦力.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241504198854424.jpg)
以导体棒AC为研究对象,分析受力,如图.
其中,安培力大小
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150419901575.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150420041876.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150420150677.png)
由①得,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241504202131117.png)
由②得,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150420275706.png)
由牛顿第三定律得,导轨受到AC棒的压力和摩擦力各为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150420338737.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150420431607.png)
点评:做此类型的问题时安培力是桥梁,关键是安培力的方向判断和大小计算.
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目