某节水喷灌系统如图所示,喷口距地面的高度
,正常工作时喷水的速率
,每秒喷出水的质量
,所用的水是从井下抽取的,井中水面离地面的高度
并一直保持不变。水泵由电动机带动,电动机电枢线圈电阻
。电动机正常工作时,电动机的输入电压
,输入电流
,不计电动机的摩擦损耗,电动机的输出功率等于水泵所需要的输入功率。忽略水在管道中运动的机械能损失,水泵的输出功率与输入功率之比称为水泵的抽水效率,重力加速度
取
。求:
(1)电动机的输出功率;
(2)水泵的抽水效率
。
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32e8d8e6a39eb510638617bdc683d160.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86f752a711071211bec5e2c8b39ddca7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8751dc445cf1cc40e9677de92f34c6da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f39661daa9b79d6da58c1e22cc53b158.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd2df969e819a7a6d6e3830736b0d06b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7e6941cab5d0510345c4f78e5c110f03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c55d5ad7a0e710a5f6c0141a9ab97f6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/276509f01529d982ab21e479a4619268.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63519b11c51441dd31d22aea2e0a4d2d.png)
(1)电动机的输出功率;
(2)水泵的抽水效率
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5c1116ce7f5a1a7b57517276d5092fa.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/18/e68b99fc-71a3-4b73-9eda-50eee5e16e46.png?resizew=210)
更新时间:2023-11-17 16:38:19
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【推荐1】如图所示,光滑水平面上有一足够长的小车M紧靠桌子左端,且上表面与水平桌面相平.小车右端放有一小滑块
(可视为质点).桌面上的A点有一小物块
(可视为质点)并与弹簧的左端接触但不拴接,轻弹簧D右端固定且处于原长状态.某时刻起用水平向右的推力将
缓慢推至B点时,弹簧在弹性限度内被压缩,撤去推力,此后
沿桌面滑到桌子边缘C时速度大小为2m/s,并与小车右端的滑块
相碰,最后
停在小车上距右端1.2m处,物块
停在小车上距右端0.5m处.已知小车M质量为3.5kg,小物块
质量为1kg,小滑块
质量为0.5kg,AB间距离L1=5cm,AC间距离L2=90cm,
与桌面间动摩擦因数1=0.2,
、
与小车表面间的动摩擦因数2=0.1,g取10m/s2,求:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/6/25/de89334c-2c4d-4052-ba8f-78289c13be6c.png?resizew=331)
(1)
被推到B点时.弹簧的弹性势能;
(2)小车M最后的速度大小;
(3)滑块
与车相对静止时m2到桌面A点的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fbd67f60f04c278bdd867fdb3979dfb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77ab1256702aef4e9f1a5eb6c12ecc96.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77ab1256702aef4e9f1a5eb6c12ecc96.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77ab1256702aef4e9f1a5eb6c12ecc96.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fbd67f60f04c278bdd867fdb3979dfb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fbd67f60f04c278bdd867fdb3979dfb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77ab1256702aef4e9f1a5eb6c12ecc96.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77ab1256702aef4e9f1a5eb6c12ecc96.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fbd67f60f04c278bdd867fdb3979dfb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77ab1256702aef4e9f1a5eb6c12ecc96.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77ab1256702aef4e9f1a5eb6c12ecc96.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fbd67f60f04c278bdd867fdb3979dfb.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/6/25/de89334c-2c4d-4052-ba8f-78289c13be6c.png?resizew=331)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77ab1256702aef4e9f1a5eb6c12ecc96.png)
(2)小车M最后的速度大小;
(3)滑块
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1fbd67f60f04c278bdd867fdb3979dfb.png)
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【推荐2】如图所示,倾角θ=
的光滑斜面固定在地面上,质量为0.5kg的物块(均可视为质点),A固定,C与斜面底端处的挡板接触,B与C通过轻弹簧相连且均处于静止状态,A、B间的距离d=3m.现释放A,一段时间后A与B发生碰撞,A、B碰撞为弹性碰撞,碰撞后立即撤去A,取g=10m/s2,sin37°=0.6,cos37°=0.8.
![](https://img.xkw.com/dksih/QBM/2019/10/18/2314596800724992/2314819388104704/STEM/9001cf5c-eb8d-4f18-a696-9cf27f4c4f6b.png?resizew=204)
(1)求A与B碰撞前瞬间A的速度大小v0;
(2)若B沿斜面向下运动到速度为零时(此时B与C未接触,弹簧仍在弹性限度内),弹簧的弹性势能增量Ep=10.8J,求B沿斜面向下运动的最大距离x;
(3)若C刚好要离开挡板时,B的功能Ek=8.7J,求弹簧的劲度系数k.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8141d00b74eb4c50bf861e6ff0edf137.png)
![](https://img.xkw.com/dksih/QBM/2019/10/18/2314596800724992/2314819388104704/STEM/9001cf5c-eb8d-4f18-a696-9cf27f4c4f6b.png?resizew=204)
(1)求A与B碰撞前瞬间A的速度大小v0;
(2)若B沿斜面向下运动到速度为零时(此时B与C未接触,弹簧仍在弹性限度内),弹簧的弹性势能增量Ep=10.8J,求B沿斜面向下运动的最大距离x;
(3)若C刚好要离开挡板时,B的功能Ek=8.7J,求弹簧的劲度系数k.
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【推荐1】如图所示,电源电动势
,内阻
,标有“
,
”字样的灯泡L恰好能正常发光,电动机M的线圈电阻
。求
(1)通过电动机线圈的电流;
(2)电动机的输出功率;
(3)电源的总功率。
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5625a648ec4ec32091ead4af78163f83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dfd5632d8539e488c8c1af343171ff50.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cc6f3909cf85a985cc47a1ec15e788cd.png)
(1)通过电动机线圈的电流;
(2)电动机的输出功率;
(3)电源的总功率。
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/13/36366577-f00b-4f2f-8d56-73219617fafd.png?resizew=169)
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【推荐2】如图所示的电路中,电源电动势E=220V,内阻
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。求:
(1)电源总功率;
(2)电源的输出功率;
(3)电动机的效率为多少?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd4739c5b3aaa51b2d7413f9ada1a375.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/559f23fb2c79804449870959464726cc.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/35b4aaa407b96457788654b272d5877d.png)
(1)电源总功率;
(2)电源的输出功率;
(3)电动机的效率为多少?
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/31/d9837313-d7b8-413c-abcc-6ca49bc35eaa.png?resizew=251)
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