What is the work done by the force?
A.0.1J
B.2.5J
C.12J
D.37.7J
更新1:
I want clear explanation.
Phy MC~~
2007-03-31 7:33 pm
A screw jack is shown below. A worker rotates the handle with 20N for 1 revolution and the load of 50kg is raised for 5mm.The distance between the load and handle is 30cm.
What is the work done by the force?
A.0.1J
B.2.5J
C.12J
D.37.7J
What is the work done by the force?
A.0.1J
B.2.5J
C.12J
D.37.7J
回答 (2)
2007-03-31 8:21 pm
✔ 最佳答案
The screw jack is a kind of machine.For the input energy by the worker, we can calculate his work done on the handle is given by:
Work done = displacement × force
= 2π × 0.3 × 20
= 37.7 J (Answer: D)
Also, the output of the screw jack is: 50 × 10 × 0.005 = 2.5 J which is the increase in gravitational energy of the block. (Note: This is OUTPUT energy)
Then efficiency of the screw jack is given by: (2.5/37.7) × 100 % = 6.63 %
參考: My Physics knowledge
2007-03-31 8:03 pm
D.37.7J
收錄日期: 2021-05-03 06:57:47
原文連結 [永久失效]:
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