题目内容
(1)金属棒ab的最大速度;
(2)金属棒ab运动达到稳定状态后,1s钟内回路产生的焦耳热。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241154099632661.gif)
(1)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115409994577.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115409978453.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115409994577.gif)
(1)最初ab、cd均刚好保持静止。根据其受力情况可知ab、cd与导轨间最大静摩擦力
当用外力F作用ab棒时
(2分)
故ab棒开始沿导轨加速上滑,棒中产生感应电动势,回路中形成感应电流。因此,棒ab又将受到安培力作用。当ab棒所受外力的合力为零时,金属棒ab达最大速度,设为Vm,则
(2分) 其中![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115410243527.gif)
I (2分)
故
考虑此时棒cd的受力情况,应有
仍然保持静止。(2分)
所以有
(2分)联立以上方程可得
(2分)
(2)由以上方程中解得
(3分)
则回路所产生的焦耳热
(3分)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115410181602.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115410197607.gif)
故ab棒开始沿导轨加速上滑,棒中产生感应电动势,回路中形成感应电流。因此,棒ab又将受到安培力作用。当ab棒所受外力的合力为零时,金属棒ab达最大速度,设为Vm,则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115410212600.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115410243527.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115410259356.gif)
故
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115410275419.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115410306843.gif)
所以有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115410321526.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115409978453.gif)
(2)由以上方程中解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115410337262.gif)
则回路所产生的焦耳热
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115409994577.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目