1 . 如图所示,一个半径为r的金属圆环水平固定,长为r且电阻为的金属杆a沿半径放置,其一端与圆环接触良好,另一端固定在过圆心的导电竖直转轴
上,金属杆a随转轴以角速度
匀速转动。圆环内存在竖直向下的磁感应强度大小为
的匀强磁场,圆环边缘及转轴分别与水平放置且间距为L的粗糙金属轨道
相连。足够长的光滑绝缘轨道
与金属轨道平滑连接,且
处在竖直向下的磁感应强度大小为
的匀强磁场中。垂直轨道放置的金属杆b,长为L、质量为m、电阻为
,与轨道的动摩擦因数为
。绝缘轨道
上放置一个质量为M、总电阻为
的“
”形金属框
,它的三个边长均为L。初始时,线框的
边右侧区域存在竖直向下的磁感应强度大小为
的匀强磁场。已知
,
,重力加速度为g,不考虑框架中的电流产生的磁场影响,除已给电阻外其它电阻值均忽略不计,最大静摩擦力和滑动摩擦力大小相等。
(2)当角速度为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5180891493b5574640c3c5cecec78ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
(3)当角速度为时,金属杆b与“
”形金属框碰撞形成一闭合的正方形方框后,一起进入右侧磁场区域,求运动稳定后“
”形框产生的焦耳热(结果用分数表示)。
(1)小球抛出时的初速度大小
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f58888df91890a19a1aa7511d19703f.png)
(2)x轴下方磁场的磁感应强度大小B;
(3)小球从抛出到第二次进入x轴下方的复合场的时间t。
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/20/9914f8d5-b761-4618-9954-f00889d34c5e.png?resizew=285)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ee31829d0d4d5f779a957d7df8058ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2af31a8d791f28399fc13be3250136dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc3b42c4ad90167f1b7bc60044d971ec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f58888df91890a19a1aa7511d19703f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ac09dc1ca2cdd7aef28c218763d3e4d.png)
(1)求粒子发射的位置坐标;
(2)为使粒子能打在荧光屏上的
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
(3)为使粒子能打在荧光屏上的
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/23/b6216e98-9a20-4e06-afb3-777b1fd8ff66.png?resizew=190)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/462cd06b78b59b52b68623fd285229da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57124599d0a72bf788f08ce442a85600.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bccb5107486df9c231bb5744c788c663.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c02bc0c74292b1e8f395f90935d3174.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/276509f01529d982ab21e479a4619268.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b595a24be9a1fc781779959c038c7bc3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bccb5107486df9c231bb5744c788c663.png)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/18f0281e6bbdbe08beeccb55adf84536.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bccb5107486df9c231bb5744c788c663.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11bc05f41215f9894e11d1df0465751a.png)
(2)匀强磁场的磁感应强度
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
(3)金属框穿过磁场区域的过程中电阻
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
【可供参考的知识:两个电动势相同的电源并联后对电路供电时,电源的总电动势等于单个的电源的电动势,电源的总电阻等于两个电源内阻的并联电阻。】
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/22/578e12c1-11dd-471b-b6b5-c7d89367ba1f.png?resizew=121)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2606b89219cbba927ff39dc7e84ac6e.png)
(1)小球从A点抛出时的初速度大小;
(2)要使小球不进入磁场Ⅱ,匀强磁场的磁感应强度大小应满足什么条件?
(3)若小球第一次在磁场Ⅰ中运动的偏向角为90°,进入磁场Ⅱ中运动到某位置时撤去磁场Ⅱ,此后小球第二次在磁场Ⅰ中的运动轨迹恰好与MN相切,则撤去磁场Ⅱ时小球的位置离PQ的距离为多少?
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/7/b762462c-62be-4e43-99d5-201017cc39d3.png?resizew=144)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/594a9c33a588802263d538d5244240ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ee31829d0d4d5f779a957d7df8058ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5a7c83c30c08a190a905c44dcb94e3b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc31029b64deceffde4c57293efddeef.png)
(1)若粒子能垂直y轴离开磁场,则初速度的最大值;
(2)若粒子离开磁场后能垂直经过x轴.则其在第I象限内运动的时间t;
(3)若在(2)中情况下.在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ee31829d0d4d5f779a957d7df8058ab.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/20/c9e032a3-bb9b-4d67-9dce-89d305ace174.png?resizew=168)
7 . 2023年杭州亚运会女子米接力赛中,中国队最终以43秒39的成绩夺冠。如图所示,在
米接力比赛中,当甲运动员以
的速度匀速通过起跑标记点A时,乙运动员在接力区起点
由静止开始以
的加速度匀加速预跑,加速至
后保持匀速直线运动。已知甲运动员在完成交接棒前速度保持不变,接力区长度为
。求:
(1)乙运动员能否在接力区加速至;
(2)若A、B两点间的距离为12m,求完成交接棒时乙预跑的距离;
(3)为了保证甲、乙在接力区完成交接棒,A、B点间的最大距离是多少。
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/316ecb1589c3cc179e2f62507020771e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e70521af56475e285c933307e70117e2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c27eda162792128da25f541303a3088.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c27eda162792128da25f541303a3088.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/316ecb1589c3cc179e2f62507020771e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/316ecb1589c3cc179e2f62507020771e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c27eda162792128da25f541303a3088.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/316ecb1589c3cc179e2f62507020771e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c27eda162792128da25f541303a3088.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/316ecb1589c3cc179e2f62507020771e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e70cc707cf0b979edc07072c34ba7ce3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b128e21c09838cdc7c3a43d97b0fba7d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c27eda162792128da25f541303a3088.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ced8cbb708a1c7b367d9a14c8eaa691b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/316ecb1589c3cc179e2f62507020771e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb7ec37b33cdadbf9ad6872a363c0fd3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/276509f01529d982ab21e479a4619268.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c4ee1b7d06ac4c703e4c086b425c9c5.png)
(1)物块
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c27eda162792128da25f541303a3088.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/316ecb1589c3cc179e2f62507020771e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c27eda162792128da25f541303a3088.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43dfcc2ac8d9f96ab302ea84969e0ee5.png)
(2)物块
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c27eda162792128da25f541303a3088.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/316ecb1589c3cc179e2f62507020771e.png)
(3)在第一次碰撞之后的整个过程中,物块
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c27eda162792128da25f541303a3088.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/35893041a02be39c9d0c1e9b329556eb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/276509f01529d982ab21e479a4619268.png)
A.金属杆中的电流方向从![]() ![]() |
B.金属杆出磁场时的速率为![]() |
C.通过金属线框上侧短边的电荷量为![]() |
D.金属线框产生的焦耳热为![]() |
A.![]() | B.![]() | C.![]() | D.![]() |