![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e47764ad5675f2f70ffe152f19a3e169.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d783ba1adf57122afc48768f12dab4f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccc94f2ea411c691d91a4fc6665c24ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/59242de3167f3dfd89e4024318748ed4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f881cb9071ca8fea7cef4ab8d4865589.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7aeb9a94e392f6759b18abed89aacc5e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42a585d18cafc764ef0dc144feedce19.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf189a86ac788e61722281a7b1ed7b8e.png)
(1)当cd棒的速度
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af3fd9869fab0a35575a6742f0643574.png)
(2)0~1s内通过ab棒的电量;
(3)0~1s内cd棒运动的位移;
(4)0~1s内cd棒产生的焦耳热。
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/6/7b02a4b7-5a05-41f7-a226-1deef552c2db.png?resizew=188)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/772562a411cb35b12e8a5878ddaa9de1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85eeeb4230f7bdc47fa9a908653610f1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef0ed982fe3627a5c6868d55d03befbf.png)
(1)求电子的初速度大小
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f58888df91890a19a1aa7511d19703f.png)
(2)求落在荧光屏最右侧的电子进入圆形磁场时的x坐标;
(3)若入射电子在虚线处均匀分布,且各位置只有1个,求落在荧光屏上“两次发光区域”和“一次发光区域”的电子数之比。
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/171102a883b22fe6ca578efc8926f5b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3606c4a853a6a34cb7f33bea81b15a1f.png)
求:
(1)空心柱内封闭气体的压强是多少?
(2)假设气泵每次可将压强为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3606c4a853a6a34cb7f33bea81b15a1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21c280c5f4ae649c3bb1f720633c886c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d1e589464d06c142481806fb43728bf.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/23/da534470-353e-40d1-9202-7c90341c97d1.png?resizew=289)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55d8248e69aff7f67a127b7d11524fbe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3623d51024ebfd95593c9895d8cb95d8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fda5655ef480683a2d3b74f0b523439.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/583f63789475e301bf9296267cd8abe9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7aeb9a94e392f6759b18abed89aacc5e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3d14fb9c919bbc88beaa969bcc42704.png)
(1)导体棒与导轨之间的动摩擦因数;
(2)匀强磁场的磁感应强度的大小;
(3)导体棒穿越磁场过程中拉力F做的功。
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/16/9bdb39ba-642f-4955-a79f-9c744f5d8d87.png?resizew=218)
A.安培力对两根金属棒的冲量相同 |
B.安培力对ab做的功等于ab动能的增量 |
C.cd克服安培力做的功等于整个回路中产生的焦耳热 |
D.ab和cd最终会以相同的速度做匀速直线运动 |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56d266a04f3dc7483eddbc26c5e487db.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/16/866a19ef-50bc-4caf-9a65-aec7a47a08bd.png?resizew=239)
A.小球在轨道最低点的机械能最大 |
B.小球在轨道最低点对轨道的压力最大 |
C.改变初速度大小,小球可能中途脱离“凹形”轨道 |
D.无论怎样改变初速度大小,小球都不能通过Q点 |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5dee915e2fb7b8a1f4328473f9c18ba7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75a38270f6cb38d1dcab28a8cc8f0589.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ccf0ab33344a142a817b80711bb5c6c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca8480527bd42837fd4f5775045eddc8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46a6a294d3d7206bcdde5b943dbe94f0.png)
求:
(1)石子从地面抛到槽顶端所用的时间;
(2)石子即将到达地面时,槽底部对石子的支持力大小(保留3位有效数字)。
8 . 如图1所示是依附建筑物架设的磁力缓降高楼安全逃生装置,我们可以将下降过程进行如下建模:一根足够长的空心铜管竖直放置,使一枚直径略小于铜管内径,质量为M的圆柱形强磁铁从管内某处由静止开始下落,如图2所示,该强磁铁下落过程中,可以认为铜管中的感应电动势大小与强磁铁下落的速度成正比,且强磁铁周围铜管的有效电阻是恒定的,强磁铁机械能耗散的功率等于其受到的阻力大小与下落速度大小的乘积,已知重力加速度g,强磁铁在管内运动时,不与内壁摩擦,不计空气阻力。
(1)请在图3中定性画出该强磁铁下落过程中的图像;
(2)当强磁铁从静止开始下落t时间后达到最大速度,求此过程强磁铁的下落高度h;
(3)如果在图2强磁铁的上面粘一个质量为m的绝缘橡胶块,推导它们下落的最大速度。
9 . 如图所示,两根型平行光滑金属导轨固定在绝缘水平面上,左、右两侧导轨间距分别为l和
,处于竖直向下的磁场中,磁感应强度大小分别为
和B。已知导体棒ab的电阻为R、长度为l,导体棒cd的电阻为
、长度为
,cd的质量是ab的3倍。两棒中点之间连接一原长为L轻质绝缘弹簧。现将弹簧拉伸至
后,同时由静止释放两导体棒,两棒在各自磁场中往复运动直至停止,弹簧始终在弹性限度内。整个过程中两棒保持与导轨垂直且接触良好,导轨足够长,电阻不计。下列说法正确的是( )
A.整个过程中,回路中始终产生顺时针方向的电流 |
B.整个运动过程中,ab与cd的路程之比为3∶1 |
C.cd棒克服安培力做的功等于cd棒产生的热量 |
D.整个运动过程中,通过cd的电荷量为![]() |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80885d5666acdb1d68fefc7c703a7dd9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e255ee531e84d19ba14cfd3b59d7d864.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea1e8babee63bfc889ae5a34632284bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c559d49cce3dfafff578e2d3fc6cd13d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea1e8babee63bfc889ae5a34632284bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e87dc6b4e0faf3727d8598adcf4bf324.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff4489d9b83072184c0e1d6b09be50ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9059a390616d736a4db76e3ba4716a81.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea1e8babee63bfc889ae5a34632284bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff4489d9b83072184c0e1d6b09be50ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea1e8babee63bfc889ae5a34632284bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a831fae871c9028a347e59294f7422ec.png)
(1)求第一次碰撞后瞬间
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff4489d9b83072184c0e1d6b09be50ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea1e8babee63bfc889ae5a34632284bc.png)
(2)如果两小球第二次第三次碰撞都发生在电场中,则在第二次与第三次碰撞之间,有一个时刻
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea1e8babee63bfc889ae5a34632284bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d7d25313067f3e11f68da496344c4956.png)
(3)现要求两小球可以发生第三次碰撞,求电场水平宽度满足的条件。
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/3/92ded31d-9b41-41f0-926d-ff11fc09b1f1.png?resizew=239)