题目内容
(1)除R以外,其余部分的电阻均不计,求R的阻值;
(2)当棒的位移为100 m时,其速度已经达到10 m/s,求此过程中电阻上产生的热量。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241143320785303.jpg)
(1)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114332093690.gif)
(2)Q=20J。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114332093690.gif)
(2)Q=20J。
(1)由图象可知,导体棒刚运动时加速度
,
设它受到的摩擦力为f,由牛顿运动定律得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114332249435.gif)
解得f="0.2" N
导体棒匀速运动时,由力的平衡得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114332265428.gif)
且![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114332280644.gif)
解得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114332093690.gif)
(2)根据能量守恒得![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114332343643.gif)
解得Q=20J。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114332202454.gif)
设它受到的摩擦力为f,由牛顿运动定律得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114332249435.gif)
解得f="0.2" N
导体棒匀速运动时,由力的平衡得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114332265428.gif)
且
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114332280644.gif)
解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114332093690.gif)
(2)根据能量守恒得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114332343643.gif)
解得Q=20J。
![](http://thumb2018.1010pic.com/images/loading.gif)
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