ZHDY7-2*如图所示，一根长为L的金属细杆ab绕竖直轴MN以角速度ω在水平面内旋转．MN在离细杆a 端L /4 处．若已知地磁场在竖直方向的分量为B．求ab两端间的电势差为（）http://image.zhihuishu.com/zhs/onlineexam/ueditor/201808/b75c46ee0f5045a289af572e9b1f813a.png

A .https://assets.asklib.com/psource/2015103013292779880.jpg B .https://assets.asklib.com/psource/201510301329465757.jpg C .https://assets.asklib.com/psource/2015103013300053333.jpg D .https://assets.asklib.com/psource/2015103013301585099.jpg

A . A B . B C . C D . D

A . （1／12）ml ω B . （7／24）ml ω C . （7／48）ml ω D . （7／96）ml ω

A . A B . B C . C D . D

A .https://assets.asklib.com/psource/2015103014503984624.jpg B .https://assets.asklib.com/psource/2015103014505084240.jpg C .https://assets.asklib.com/psource/2015103014510485319.jpg D .https://assets.asklib.com/psource/2015103014512148828.jpg

A .https://assets.asklib.com/images/image2/201705110946166076.png B .https://assets.asklib.com/images/image2/2017051109461984184.png C .https://assets.asklib.com/images/image2/2017051109462167686.png D .https://assets.asklib.com/images/image2/2017051109462264555.png

A . ['['0B .https://assets.asklib.com/psource/2015110210461670074.png C .https://assets.asklib.com/psource/201511021046197517.png D .https://assets.asklib.com/psource/2015110210462335569.png

A . A B . B C . C D . D

<img src='https://img2.soutiyun.com/ask/uploadfile/5088001-5091000/0a17aa9b2811a784c73e007ea80e7b60.jpg' /> A．<img src='https://img2.soutiyun.com/shangxueba/ask/5088001-5091000/5089780/onerrorimg.jpg' /> B．<img src='https://img2.soutiyun.com/shangxueba/ask/5088001-5091000/5089780/onerrorimg.jpg' /> C．<img src='https://img2.soutiyun.com/shangxueba/ask/5088001-5091000/5089780/onerrorimg.jpg' /> D．<img src='https://img2.soutiyun.com/shangxueba/ask/5088001-5091000/5089780/onerrorimg.jpg' />

如图所示，一均匀细杆长为，质量为m，平放在摩擦系数为u的水平桌面上，设开始时杆以角速度<img src='https://img2.soutiyun.com/ask/2021-02-08/981629300873302.png' />绕过中心o且垂直与桌面的轴转动，试求：(1)作用于杆的摩擦力矩;(2)经过多长时间杆才会停止转动。 <img src='https://img2.soutiyun.com/ask/2021-02-08/981629320354417.png' />

<img src='https://img2.soutiyun.com/shangxueba/ask/18627001-18630000/18627235/2016071917373619874.jpg' /><img src='https://img2.soutiyun.com/shangxueba/ask/18627001-18630000/18627235/201607191737384184.jpg' /> A．A B． B C． C D． D

<img src='https://img2.soutiyun.com/ask/2020-07-08/963065823078817.png' />

A．<img src='https://img2.soutiyun.com/shangxueba/ask/17043001-17046000/17044858/ed023e8-chaoxing2016-608676.png' /> B．<img src='https://img2.soutiyun.com/shangxueba/ask/17043001-17046000/17044858/4bd13e7-chaoxing2016-608677.png' /> C．<img src='https://img2.soutiyun.com/shangxueba/ask/17043001-17046000/17044858/341e6d6-chaoxing2016-608678.png' /> D．<img src='https://img2.soutiyun.com/shangxueba/ask/17043001-17046000/17044858/e3d2d6a-chaoxing2016-608679.png' />

A.0 B.39／(4L) C.39／(2L) D.69／L

如图5-30所示,AB为一根长为2L的带电细棒,左半部均匀带有负电荷一q,右半部均匀带有正电荷q. O点在棒的延长线上,距A端的距离为L;P点在棒的垂直平分线上,到棒的垂直距离为L.以棒的中点C为电势的零点。求O点电势和P点电势。 <img src='https://img2.soutiyun.com/ask/2020-04-30/957108186820535.png' />

<img src='https://img2.51aidian.com/ask/2020-12-17/977086075083582.png' />

(1)0点的磁感应强度; (2)转动导线的磁矩 <img src='https://img2.soutiyun.com/ask/2020-07-09/963136781771038.png' />

<img src='https://img2.soutiyun.com/ask/2020-04-21/95630853844841.png' /> (1)子弹与杆开始共同运动的角速度; (2)子弹与杆共同摆动能达到的最大角度。

<img src='https://img2.soutiyun.com/shangxueba/ask/50259001-50262000/50261019/963137010554123.png' />

(1)下抛初速度v0。 (2)在最低点B时，细杆对球的作用力。 <img src='https://img2.soutiyun.com/ask/2020-07-08/963065468823554.png' />

如图所示，一直流电源(电压为U0，内阻为零)经一集中参数电阻R合闸于AB长线上。AB长为l，波阻抗为Z，波在其上传播速度为υ。B点开路，C为AB上一点，且以K合闸时刻为τ=0，试绘出R=Z时，uc(t)的波形。 <img src='https://img2.soutiyun.com/ask/2019-10-24/940761872902012.png' />