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如图 所示的是甲、乙两个滑轮组提升重物.物重G1和G2之比是2:1;甲滑轮组中动滑轮重G甲与G1之
题目内容:
如图 所示的是甲、乙两个滑轮组提升重物.物重G1和G2之比是2:1;甲滑轮组中动滑轮重G甲与G1之比是1:5;乙滑轮组中两个动滑轮总重G乙与G2之比是3:5(不计摩擦、绳重)则甲、乙两个滑轮组的机械效率之比是______.
优质解答
由题知,G1:G2=2:1,
设G1=20N,则G2=10N,
∵G甲:G1=1:5,
∴G甲=4N,
∵G乙:G2=3:5,
∴G乙=6N,
∵不计摩擦、绳重,
∴η甲=G1h (G1+G甲)h
=G1 G1+G甲
=20N 20N+4N
=20N 24N
,
η乙=G2h (G2+G乙)h
=G2 G2+G乙
=10N 10N+6N
=10N 16N
,
∴η甲:η乙=20N 24N
:10N 16N
=4:3.
故答案为:4:3.
优质解答
由题知,G1:G2=2:1,
设G1=20N,则G2=10N,
∵G甲:G1=1:5,
∴G甲=4N,
∵G乙:G2=3:5,
∴G乙=6N,
∵不计摩擦、绳重,
∴η甲=
G1h |
(G1+G甲)h |
G1 |
G1+G甲 |
20N |
20N+4N |
20N |
24N |
η乙=
G2h |
(G2+G乙)h |
G2 |
G2+G乙 |
10N |
10N+6N |
10N |
16N |
∴η甲:η乙=
20N |
24N |
10N |
16N |
故答案为:4:3.
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