配套习题- 灵活运用机械效率公式解题（3） -【青果学院】

挑战习题

1/5单选题

难度：

一工人用如图所示装置，打捞水中的铁箱。铁箱体积为39dm³质量为79kg,忽略绳重和摩擦，滑轮组的机械效率为80%，则动滑轮重力为（）（g=10N/kg）

A	120N
B	75N
C	60N
D	100N

提示1：: PHA+5rGC5Ye66ZOB566x55qE6YeN5Yqb5ZKM5rWu5YqbPC9wPg==

提示2：: PHA+6ZOB566x5a+55Yqo5ruR6L2u55qE5ouJ5Yqb5YGa55qE5Yqf5Li65pyJ55So5YqfPC9wPg==

提示3：: PHA+5qC55o2u5py65qKw5pWI546H5rGC5ruR6L2u6YeN5YqbPC9wPg==

正确答案：RA==

PGRpdj7op6PvvJpHPW1nPTc5ME4sRjxzdWI+5rWuPC9zdWI+Pc+BPHN1Yj7msLQ8L3N1Yj5ndj0zOTBOLOaJgOS7pc63PTxpbWcgc3JjPSJodHRwczovL3AyLnFpbmdndW8uY29tL0cxL00wMC8wMS9ERi9yQkFDRkZNTlhYVGlKZmM1QUFBQ1JqMUViQTAwMzQucG5nIiBkYXRhLWNrZS1zYXZlZC1zcmM9Imh0dHBzOi8vcDIucWluZ2d1by5jb20vRzEvTTAwLzAxL0RGL3JCQUNGRk1OWFhUaUpmYzVBQUFDUmoxRWJBMDAzNC5wbmciIGhlaWdodD0iNDIiIHdpZHRoPSI1OSI+PTgwJe+8jEc8c3ViPkQ8L3N1Yj49MTAwTjwvZGl2Pg==

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2/5单选题

难度：

2.小亮用滑轮组提升水中重物G，当G在水中匀速上升时，拉力F₁=100N，当重物完全出水后，所用拉力为F₂=150N，动滑轮重力为50N，忽略绳重和摩擦。则重物G在露出水面前的机械效率为（）

A	83.3%
B	85%
C	75%
D	90%

提示1：: IOWvueeJqeS9k+WcqOawtOS4reaXtui/m+ihjOWPl+WKm+WIhuaekOW+l+WHuuetieW8j++8mjNGPHN1Yj4xPC9zdWI+PUctRjxzdWI+5rWuPC9zdWI+K0c8c3ViPkQ8L3N1Yj4=

提示2：: IOWvueeJqeS9k+WHuuawtOWQjui/m+ihjOWPl+WKm+WIhuaekOW+l+WHuuetieW8j++8mjNGPHN1Yj4xPC9zdWI+PUcrRzxzdWI+RDwvc3ViPg==

提示3：: IOWIqeeUqOWFrOW8j+axguacuuaisOaViOeOh+OAgg==

正确答案：QQ==

PGRpdj7op6PvvJrlr7nniankvZPlh7rmsLTlkI7ov5vooYzlj5flipvliIbmnpDlvpflh7rnrYnlvI/vvJozRjxzdWI+MTwvc3ViPj1HK0c8c3ViPkQ8L3N1Yj7vvIzlvpdHPTQwME7vvIzlr7nniankvZPlnKjmsLTkuK3ml7bov5vooYzlj5flipvliIbmnpDlvpflh7rnrYnlvI/vvJozRjxzdWI+MTwvc3ViPj1HLUY8c3ViPua1rjwvc3ViPitHPHN1Yj5EPC9zdWI+77yM5b6XRjxzdWI+5rWuPC9zdWI+PTE1ME7vvIzOtz08aW1nIHdpZHRoPTU5IGhlaWdodD00MiBzcmM9Imh0dHBzOi8vcDIucWluZ2d1by5jb20vRzEvTTAwLzAxL0RGL3JCQUNGRk1OWFhUaUpmYzVBQUFDUmoxRWJBMDAzNC5wbmciPj04My4zJTwvZGl2PjxkaXY+

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3/5单选题

难度：

3.李师傅用如图所示装置打捞质量为50kg的实心金属块，金属块在水中匀速上升过程中（始终未露出水面），滑轮组的机械效率80%,已知：动滑轮重为100N。忽略绳重与摩擦，则该金属的密度为（）（g=10N/kg）

A
B
C
D

提示1：: IOagueaNruacuuaisOaViOeOh+axgueJqeS9k+aJgOWPl+a1ruWKmw==

提示2：: IOaxguWHuueJqeS9k+eahOS9k+enrw==

提示3：: IOagueaNruWvhuW6puWFrOW8j+axguWvhuW6pg==

正确答案：Qg==

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4/5单选题

难度：

4.一工人用如图所示装置，匀速提升一金属块A，A露出水面前，滑轮组的机械效率为75%，A完全露出水面后，滑轮组的机械效率为80%，则金属块的密度为（）

A	3×10³kg/m³
B	7.5×10³kg/m³
C	4×10³kg/m³
D	5.5×10³kg/m³

提示1：: IOihqOekuuWHukHpnLLlh7rmsLTpnaLliY3nmoTmnLrmorDmlYjnjoc=

提示2：: IOihqOekuuWHukHpnLLlh7rmsLTpnaLlkI7nmoTmnLrmorDmlYjnjoc=

提示3：: IOS4pOW8j+iBlOWIl+axguWHuua1ruWKm+WSjOmHjeWKm+avlOWPr+W+lw==

正确答案：Qw==

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5/5单选题

难度：

5.工人师傅用如图所示的滑轮组，提升物体A，使物体A以0.1m/s的速度匀速上升. 此时滑轮组的机械效率为80%. 功率为90W。用同一装置提升物体B，此时机械效率为75%，（不计绳重和轴摩擦）则物体B的重力为（）

A	720N
B	750N
C	540N
D	600N

提示1：: IOeUqOWFrOW8j+ihqOekuuaPkOWNh0Hml7bnmoTmnLrmorDmlYjnjoflj4rlip/njoc=

提示2：: IOeUqOWFrOW8j+ihqOekuuaPkOWNh0Lml7bnmoTmnLrmorDmlYjnjofjgII=

提示3：: IOWwhuS4iui/sOS4ieW8j+iBlOWIl+WNs+WPr+axguW+lw==

正确答案：Qw==

PGRpdj7op6PvvJrnlLFQPUZ2LOWPr+W+l++8mjkwVz1Gw5czw5cwLjFtL3MsRj0zMDBOLOeUseacuuaisOaViOeOh+WFrOW8j+WPr+W+l0c8c3ViPkE8L3N1Yj4vKDNGKT04MCUs5b6XRzxzdWI+QTwvc3ViPj03MjBO77yM5omA5LulRzxzdWI+RDwvc3ViPj0xODBO77yM5Y+I55Sx5py65qKw5pWI546H5YWs5byPRzxzdWI+Qjwvc3ViPi8oRzxzdWI+Qjwvc3ViPitHPHN1Yj5EPC9zdWI+KT03NSXvvIzlj6/lvpdHPHN1Yj5CPC9zdWI+PTU0ME7jgII8L2Rpdj4=

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