如图,
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmtext%3E%CE%B8%3C%2Fmtext%3E%3C%2Fmath%3E)
=37°的足够长且固定的粗糙绝缘斜面顶端放有质量M=0.024kg的U型导体框,导体框的电阻忽略不计,导体框与斜面之间的动摩擦因数
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmtext%3E%CE%BC%3C%2Fmtext%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmn%3E.%3C%2Fmn%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmn%3E5%3C%2Fmn%3E%3C%2Fmath%3E)
。一电阻R=3
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmtext%3E%CE%A9%3C%2Fmtext%3E%3C%2Fmath%3E)
、长度L=0.6m的光滑金属棒CD置于导体框上,与导体框构成矩形回路CDEF,且EF与斜面底边平行。初始时CD与EF相距s
0=0.03m,让金属棒与导体框同时由静止开始释放,金属棒下滑距离s
1=0.03m后匀速进入方向垂直于斜面的匀强磁场区域,磁场边界(图中虚线)与斜面底边平行。当金属棒离开磁场的瞬间,导体框的EF边刚好进入磁场并保持匀速运动。已知金属棒与导体框之间始终接触良好,且在运动中金属棒始终未脱离导体框。磁场的磁感应强度大小B=1T、方向垂直于斜面向上,取g=10m/s
2 , sin37°=0.6,cos37°=0.8。求:
![](http://tikupic.21cnjy.com/2022/02/16/ee/f4/eef484f74681b30bbf3e8ed368dbe507.png)