配套习题- 机械效率 -【青果学苑】

1/5单选题

难度：

1.关于机械效率的下列说法中，正确的是（　　）

A	利用机械越省力，机械效率越高
B	机械做功越快，机械效率越高
C	有用功相同、总功越大机械效率越高
D	额外功相同、有用功越大的机械效率越高

正确答案：RA==

5py65qKw5pWI546H6auY5L2O5LiO5piv5ZCm55yB5Yqb5peg5YWz77yMQemAiemhuemUmeivr++8m+acuuaisOWBmuWKn+i2iuW/q++8jOWKn+eOh+i2iuWkp++8jELpgInpobnplJnor6/vvJvmnInnlKjlip/nm7jlkIzjgIHmgLvlip/otorlpKfmnLrmorDmlYjnjofotorkvY7vvIxD6YCJ6aG56ZSZ6K+v77yb5qC55o2uPGltZyB3aWR0aD0xMzIgaGVpZ2h0PTQ5IHNyYz0iaHR0cHM6Ly9wMS5xaW5nZ3VvLmNvbS9HMS9NMDAvNkUvNEEvckJBQ0oxVkFWWjN6bmpMV0FBQUVadFlJam8wODQxLnBuZyI+5Y+v55+l77yM6aKd5aSW5Yqf55u45ZCM44CB5pyJ55So5Yqf6LaK5aSn55qE5py65qKw5pWI546H6LaK6auY77yMROmAiemhueato+ehru+8jOaVhemAiUQu

2/5单选题

难度：

2.在滑轮组中动力做功100J，动滑轮对重物做功80J，则（　　）

A	有用功是100J
B	总功是100J
C	额外功是80J
D	额外功是100J

正确答案：Qg==

5Yqo5Yqb5YGa55qE5Yqf5piv5oC75Yqf77yM5omA5Lul5oC75Yqf5pivMTAwSu+8m+WKqOa7kei9ruWvuemHjeeJqeWBmueahOWKn+aYr+acieeUqOWKn++8jOaJgOS7peacieeUqOWKn+aYrzgwSu+8m+aVhemAiUIu

3/5单选题

难度：

3.分别用杠杆、动滑轮和滑轮组将同一物体举到相同的高度，做的有用功（　　）

A	杠杆最多
B	动滑轮最多
C	滑轮组最多
D	一样多

正确答案：RA==

5pys6aKY5Lit54mp5L2T55qE6YeN5Yqb5ZKM6KKr5Li+55qE6auY5bqm6YO955u45ZCM77yM5YWL5pyN54mp5L2T6YeN5Yqb5YGa55qE5Yqf5piv5pyJ55So5Yqf77yM5qC55o2u5Yqf55qE5YWs5byPVz1Gc++8jOWPr+efpeS4ieenjeaWueW8j+WBmueahOacieeUqOWKn+S4gOagt+Wkmu+8jOaVhemAiUQu

4/5单选题

难度：

4.如图所示，斜面长4m，高2m，工人用400N的力沿斜面将重为600N的箱子，从底端推到顶端．下列说法中正确的是（）

A	有用功为1800J，总功1200J
B	有用功为1200J，额外功为800J
C	总功为1600J，机械效率为75％
D	总功为800J，机械效率为75％

正确答案：Qw==

5pyJ55So5Yqf5Li677yaVzxzdWI+5pyJPC9zdWI+PUdoPTYwME7DlzJtPTEyMDBK77yb5oC75Yqf5Li677yaVzxzdWI+5oC7PC9zdWI+PUZzPTQwME7DlzRtPTE2MDBK77yb5py65qKw5pWI546H5Li677yaPGltZyB3aWR0aD01NiBoZWlnaHQ9NDkgc3JjPSJodHRwczovL3AyLnFpbmdndW8uY29tL0cxL00wMC82RS8xNi9yQkFDSmxWQVZoQ2lFbjVLQUFBQ191NWZrYWs1NDMucG5nIj4gPTEyMDBKLzE2MDBKPTc1JeOAguaVhemAiUMu

5/5单选题

难度：

5.用图甲、乙两种方式匀速提升100N的物体，已知滑轮重20N，绳重、摩擦不计，则（）

A	手的拉力：F_甲=F_乙；机械效率：η_甲=η_乙
B	手的拉力：F_甲＜F_乙；机械效率：η_甲＜η_乙
C	手的拉力：F_甲＞F_乙；机械效率：η_甲＜η_乙
D	手的拉力：F_甲＞F_乙；机械效率：η_甲＞η_乙

正确答案：RA==

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