题目内容
如图甲所示,
为水平放置的足够长的平行光滑导轨,导轨间距
,导轨左端连接一个R=2
的电阻,将一根质量
的金属棒
垂直地放置导轨上,且与导轨接触良好,导轨与
金属棒的电阻均不计,整个装置放在磁感强度B=2T的匀强磁场中,磁场方向垂直于导轨平面向下,现对金属棒施加一水平向右的拉力F,并保持拉力的功率恒为P=8W,使棒从静止开始向右运动。已知从金属棒开始运动直至达到稳定速度的过程中电阻R产生的热量
。试解答以下问题:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241230116275116.jpg)
(1)金属棒达到的稳定速度是多少?
(2)金属棒从开始运动直至达到稳定速度所需的时间是多少?
(3)金属棒从开始运动直至达到稳定速度的过程中所产生的平均感应电动势可在什么数值范围内取值?
(4)在乙图中画出金属棒所受的拉力F随时间
变化的大致图像。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011487402.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011502381.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011518215.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011534456.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011565221.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412301158065.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011596315.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241230116275116.jpg)
(1)金属棒达到的稳定速度是多少?
(2)金属棒从开始运动直至达到稳定速度所需的时间是多少?
(3)金属棒从开始运动直至达到稳定速度的过程中所产生的平均感应电动势可在什么数值范围内取值?
(4)在乙图中画出金属棒所受的拉力F随时间
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011830185.gif)
(1)
(1分)
(1分)
(1分)
(1分)
(1分)
(1分)
(1分)
(
2)
(2分)
(1分)
(3)
(1分)
(1分)
(1分)
(1分)
(1分)
即
(1分)
(4)(4分)匀速时,
,图像如图
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241230122363531.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011846434.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011846290.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011861325.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011877575.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011892268.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011908271.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011924564.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123011955888.gif)
(
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412301197072.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123012002595.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123012017238.gif)
(3)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123012033343.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123012095563.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123012126716.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123012142488.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123012173472.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123012189639.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123012204464.gif)
(4)(4分)匀速时,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123012220506.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241230122363531.jpg)
略
![](http://thumb2018.1010pic.com/images/loading.gif)
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