如图1所示,光滑的平行导电轨道水平固定在桌面上,轨道间连接一可变电阻,导体杆与轨道垂直并接触良好(不计杆和轨道的电阻),整个装置处在垂直于轨道平面向上的匀强磁场中。杆在水平向右的拉力作用下先后两次都由静止开始做匀加速直线运动,两次运动中拉力大小与速率的关系如图2所示。其中,第一次对应直线①,初始拉力大小为F
0 , 改变电阻阻值和磁感应强度大小后,第二次对应直线②,初始拉力大小为2F
0 , 两直线交点的纵坐标为3F
0。若第一次和第二次运动中的磁感应强度大小之比为k、电阻的阻值之比为m、杆从静止开始运动相同位移的时间之比为n,则k、m、n可能为( )
![](http://tikupic.21cnjy.com/2022/09/23/49/2f/492febe07310e362f0b627859ea1525b_500x209.png)
- A、k = 2、m = 2、n = 2
- B、
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmi%3Ek%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmsqrt%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmsqrt%3E%3Cmo%3E%E3%80%81%3C%2Fmo%3E%3Cmi%3Em%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmo%3E%E3%80%81%3C%2Fmo%3E%3Cmi%3En%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmsqrt%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmsqrt%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
- C、
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmi%3Ek%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmsqrt%3E%3Cmn%3E6%3C%2Fmn%3E%3C%2Fmsqrt%3E%3Cmo%3E%E3%80%81%3C%2Fmo%3E%3Cmi%3Em%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E3%3C%2Fmn%3E%3Cmo%3E%E3%80%81%3C%2Fmo%3E%3Cmi%3En%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmsqrt%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmsqrt%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
- D、
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmi%3Ek%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmsqrt%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmsqrt%3E%3Cmo%3E%E3%80%81%3C%2Fmo%3E%3Cmi%3Em%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E6%3C%2Fmn%3E%3Cmo%3E%E3%80%81%3C%2Fmo%3E%3Cmi%3En%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmath%3E)