1/5单选题
难度：
1.
小明用如图所示的滑轮组在水中打捞一个质量为54kg的铝块，在20s内将铜块匀速提升4m，（铜块没有露出水面）已知：人拉绳的功率为90W。 绳和轮的摩擦及水的阻力不计，则动滑轮的质量为（ ）（ρ铝=2.7×103kg/ m3，g=10N/kg）
| A | 5kg |
| B | 10kg |
| C | 11kg |
| D | 6kg |
- 提示1：
- PHA+55Sx5Yqf546H5YWl5omL77yM5rGC5ouJ5YqbPC9wPg==
- 提示2：
- PHA+UD1Gdiw8L3A+
- 提示3：
- PHA+MiBGPUctRjxzdWI+5rWuPC9zdWI+K0c8c3ViPuWKqDwvc3ViPjwvcD4=
正确答案：Qw==
PGRpdj7op6PvvJpGPVAvdj05MFcvMC40bS9zPTIyNU4s55SxMiBGPUctRjxzdWI+5rWuPC9zdWI+K0c8c3ViPuWKqDwvc3ViPuWPr+W+l++8jEc8c3ViPuWKqDwvc3ViPj0xMTBO77yM5omA5Lul5Yqo5ruR6L2u6LSo6YeP5Li6MTFrZy48YnI+PC9kaXY+
2/5单选题
难度：
2.
如图所示，小亮用不变的功率拉绳。从水中打捞一个质量为95kg的合金块，合金块没有露出水面前，在20s内被匀速提升了4m，已知：动滑轮质量为5kg。 绳和轮的摩擦及水的阻力不计，则合金块出水后上升的速度为（ ）（ρ合金=3.8×103kg/ m3，g=10N/kg）
| A | 0.2m/s |
| B | 0.15m/s |
| C | 0.18m/s |
| D | 0.3m/s |
- 提示1：
- PHA+5YWI5rGC5Ye65rC05YmN55qE5ouJ5YqbPC9wPg==
- 提示2：
- PHA+5YaN5rGC5Ye65rC05ZCO55qE5ouJ5YqbPC9wPg==
- 提示3：
- PHA+55Sx5Yqf546H5LiN5Y+Y77yM5Y2z5Y+v5rGC5Ye66YCf5bqmPC9wPg==
正确答案：RA==
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
3/5单选题
难度：
3.如图所示，小刚用滑轮组以相同的速度先后竖直向上匀速提升物体A和物体B。提升物体A时，他做功的功率为P1；提升物体B时，他做功的功率为P2,且P2=2 P1。忽略绳重及摩擦。已知动滑轮重100N,物体mA=50kg。 则物体B的质量为（ ）
| A | 130kg |
| B | 120kg |
| C | 110kg |
| D | 50kg |
- 提示1：
- IFA9RnY=
- 提示2：
- IOeUseWKn+eOh+avlOaxguaLieWKm+avlA==
- 提示3：
- IDIgRj1HK0c8c3ViPuWKqDwvc3ViPg==
正确答案：Qw==
PGRpdj7op6PvvJrnlLHku6Xnm7jlkIznmoTpgJ/luqblhYjlkI7nq5bnm7TlkJHkuIrljIDpgJ/mj5DljYfniankvZNB5ZKM54mp5L2TQu+8jOWPiFA8c3ViPjI8L3N1Yj49MlA8c3ViPjE8L3N1Yj7vvIzlj6/lvpdGPHN1Yj4yPC9zdWI+PTIgRjxzdWI+MTwvc3ViPu+8jDJGPHN1Yj4xPC9zdWI+PUc8c3ViPkE8L3N1Yj4rRzxzdWI+5YqoPC9zdWI+77yM5b6XRjxzdWI+MTwvc3ViPj0zMDBO77yMRjxzdWI+Mjwvc3ViPj02MDBO77yM5omA5LulRzxzdWI+Qjwvc3ViPj0xMTAwTu+8jG08c3ViPkI8L3N1Yj49MTEwa2fjgII8L2Rpdj4=
4/5单选题
难度：
4.如图所示，B浸没在水中，A匀速向右滑动，已知：𝑚𝐴=10𝑘𝑔, ，𝑚𝐵=6𝑘𝑔,𝑣1=0.5𝑚/𝑠，𝜌𝐵=2.5×103𝑘𝑔/𝑚3 ，动滑轮质量为0.4𝑘𝑔 。现撤去容器，用力F向左拉物块A，B以速度𝑣2=0.2m/s的速度匀速上升， 拉力F的功率为（）（𝑔=10𝑁/𝑘𝑔) 
| A | 25W |
| B | 20.8W |
| C | 10.4W |
| D | 22.6W |
- 提示1：
- IOeJqeS9k+WQkeWPs+enu+WKqOaXtu+8jOmAmui/h+WPl+WKm+WIhuaekO+8jOW+l+WHuuaRqeaTpuWKm2Y9MjBO77yM
- 提示2：
- IOeJqeS9k+WQkeW3pui/kOWKqOaXtu+8jOmAmui/h+WPl+WKm+WIhuaekO+8jOW+l+WHuuaLieWKm0Y9NTJO
- 提示3：
- IOeUsVA9RnbljbPlj6/msYLlvpc=
正确答案：Qg==
PGRpdj7op6PvvJrniankvZPlkJHlj7Pnp7vliqjml7bvvIzpgJrov4flj5flipvliIbmnpDvvIwyZj1HPHN1Yj5CPC9zdWI+LUY8c3ViPua1rjwvc3ViPitH5Yqo77yM5b6X5Ye65pGp5pOm5YqbZj0yME7vvIzniankvZPlkJHlt6bov5Dliqjml7bvvIzpgJrov4flj5flipvliIbmnpDvvIwyZj1HPHN1Yj5CPC9zdWI+ICtH5b6X5Ye65ouJ5YqbRj01Mk7vvIznlLFQPUZ25Y2z5Y+v5rGC5b6XUD0yMC44Vy48L2Rpdj4=
5/5单选题
难度：
5.
下图是电梯结构示意图。A为电梯厢，厢底有两个动滑轮B；C为配重。电动机提供拉力F 。现小明从一楼乘坐电梯，电梯厢以0.4m/s的速度匀速上升，拉力为F1，F1的功率为5kW。上升到3楼，小刚进入电梯厢。电梯厢仍以0.4m/s的速度匀速上升，已知：小明质量为50kg，小刚质量为100kg；此时电动机拉力为F2，则拉力F2的功率为（ ）（不计绳重及滑轮摩擦，g取10N/kg）
| A | 6KW |
| B | 5.5KW |
| C | 5.4KW |
| D | 5.2KW |
- 提示1：
- PHA+55SxRjxzdWI+MTwvc3ViPuWKn+eOh+WFiOaxgkY8c3ViPjE8L3N1Yj7nmoTlpKflsI/vvIw8L3A+
- 提示2：
- PHA+5YaN55SxRjxzdWI+MTwvc3ViPuaxguWHuueUteair+WOoueahOmHjeWKmzwvcD4=
- 提示3：
- PHA+5YaN55SxRjxzdWI+Mjwvc3ViPuaxguWKn+eOhzwvcD4=
正确答案：Qw==
PGRpdj7op6PvvJpQPHN1Yj4xPC9zdWI+PUY8c3ViPjE8L3N1Yj52PHN1Yj4xPC9zdWI+LOS7o+WFpeaVsOWAvOWPr+W+l0Y8c3ViPjE8L3N1Yj49NjI1ME4sMiBGPHN1Yj4xPC9zdWI+PUc8c3ViPuWwj+aYjjwvc3ViPitHPHN1Yj7moq88L3N1Yj7vvIxHPHN1Yj7moq88L3N1Yj49MTIwMDBO44CCMkY8c3ViPjI8L3N1Yj49RzxzdWI+5bCP5piOPC9zdWI+KyBHPHN1Yj7lsI/liJo8L3N1Yj4rRzxzdWI+5qKvPC9zdWI+PGJyPjwvZGl2PjxkaXY+RjxzdWI+Mjwvc3ViPj02NzUwTiwgUDxzdWI+Mjwvc3ViPj1GPHN1Yj4yPC9zdWI+djxzdWI+Mjwvc3ViPj01NDAwVy48YnI+PC9kaXY+