题目内容
如下图水平金属导轨的间距为1m,处在一个竖直向上的匀强磁场中,磁感应强度B=2T,其上有一个与之接触良好的金属棒,金属棒的电阻R=1Ω,导轨电阻不计,导轨左侧接有电源,电动势E=10V,内阻r=1Ω,某时刻起闭合开关,金属棒开始运动,已知金属棒的质量m=1kg,与导轨的动摩擦因数为0.5,导轨足够长。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082414084784412957.png)
问:(1)金属棒速度为2m/s时金属棒的加速度为多大?
(2)金属棒达到稳定状态时的速度为多大?
(3)导轨的右端是一个高和宽均为0.8m的壕沟,那么金属棒离开导轨后能否落到对面的平台?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082414084784412957.png)
问:(1)金属棒速度为2m/s时金属棒的加速度为多大?
(2)金属棒达到稳定状态时的速度为多大?
(3)导轨的右端是一个高和宽均为0.8m的壕沟,那么金属棒离开导轨后能否落到对面的平台?
(1)
(2)
(3)不能
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140847906846.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140848000910.png)
(1)感应电动势
①
且产生的感应电流其方向与电路电流方向相反,则此时电路的实际电压:
②
③
—④
(2)金属棒达到稳定状态,即
——⑤
则:
⑥
得:
⑦
由
得:
⑧
(3)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140848764169.png)
⑨
⑩
得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140849014653.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241408480471074.png)
且产生的感应电流其方向与电路电流方向相反,则此时电路的实际电压:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140848094849.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241408481561844.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140847906846.png)
(2)金属棒达到稳定状态,即
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140848250491.png)
则:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140848452663.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140848499944.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140848546670.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140848593817.png)
由
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140848655509.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140848000910.png)
(3)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140848764169.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140848811907.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140848842420.png)
得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140848967476.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140849014653.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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