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Physics pulley problem

  • Thread starter livvy07
  • Start date
  • #1
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Homework Statement



we did a lab on pulleys. The weight lifted was 19.62 N. It rose 0.20 meter with us applying a lifting force of 11 N and pulling the rose a distance of 0.16.


The Attempt at a Solution


I tried to find the efficiency of the pulley, so E=work out/work in
so work out=FD=(19.62)(0.20)=3.92
and work in=FD=(11)(0.16)=1.76
yet the work output cant be greater than the work input, so I'm clearly doing something wrong.

Any ideas? Is it a math error or bad lab results? Any help would be great :)
 

Answers and Replies

  • #2
Doc Al
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It's not a math problem. Those measurements don't make sense. How did you measure the applied force and distances?
 
  • #3
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oh no. That means the whole lab is wrong, but I'm doing the math right?
We measured the applied force with a spring scale and the distances with a ruler. i think the distances are completely wrong now...
 
  • #4
Doc Al
Mentor
44,877
1,129
That means the whole lab is wrong, but I'm doing the math right?
Yep, your math is fine. :frown:
 
  • #5
6
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oh well. Thanks for the help though! Guess I'll have to start making up numbers
 

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