题目内容
如图所示,两根平行金属导轨MN、PQ相距为d=1.0m,导轨平面与水平面夹角为
,导轨上端跨接一定值电阻R=1.6
,导轨电阻不计.整个装置处于方向垂直导轨平面向上、磁感应强度大小B=1.0T的匀强磁场中,金属棒ef垂直于MN、PQ静止放置,且与导轨保持良好接触,其长刚好为d、质量度m=0.10kg、电阻r=0.40
,距导轨底端的距离
。另一根与金属棒平行放置的绝缘棒gh长度也为d,质量为m/2,从轨道最低点以速度
沿轨道上滑并与金属棒发生正碰(碰撞时间极短),碰后金属棒沿导轨上滑
后再次静止。测得从碰撞至金属棒静止过程中电阻R上产生的焦耳热为
。已知两棒与导轨间的动摩擦因数均为
,取
,求:
(1)碰后瞬间两棒的速度
(2)碰后瞬间金属的加速度
(3)金属棒在导轨上运动的时间![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241150483644021.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048005268.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048067195.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048067195.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048114413.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048130435.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048145433.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048332434.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048332319.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048364439.gif)
(1)碰后瞬间两棒的速度
(2)碰后瞬间金属的加速度
(3)金属棒在导轨上运动的时间
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241150483644021.jpg)
(1)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048379414.gif)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048395427.gif)
(3)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048410389.gif)
(1)碰前:
对
由动能定理:
① (1分)
………………………………………………………………② (1分)
碰后:
对
由能量守恒:
………③ (2分)
…………………………………………………………④ (1分)
解方程组
方向沿导轨向上…………………………………⑤ (1分)
相碰:由动量守恒
……………………………⑥ (2分)
方向沿导轨向下…………………………………………⑦ (1分)
(2)
………………………………………⑧ (1分)
………………………………………………………⑨ (1分)
……………………………………⑩ (1分)
方向沿导轨向下…………………………………………11(1分)
(3)
………………………………………………………12(1分)
…………………………………………13 (1分)
…………………………………14(1分)
由动量定理:
…………15(2分)
……………………………………………… 16(1分)
解方程
…………………………………… 17(1分)
对
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048426226.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241150485351081.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048566402.gif)
碰后:
对
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048582220.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048598928.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048613534.gif)
解方程组
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048629408.gif)
相碰:由动量守恒
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048644604.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048379414.gif)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048707568.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048707519.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048722778.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048395427.gif)
(3)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048941446.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048972653.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048988821.gif)
由动量定理:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115049003901.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115049019384.gif)
解方程
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115048410389.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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