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Simple Force Problem

  • #1

Homework Statement


An 80 KG man is standing on the platform of mass 20 KG is lowering him self down using a massless cable passing over two pullies. If his downward acceleration is .2 M/S^2, find force exerted by the man on the cable.


Homework Equations


I thought it was a simple
F=M*A


The Attempt at a Solution


F= (100 Kg) * (.2 m/s^2)
F= 20 N
 

Answers and Replies

  • #2
30
0
That is correct, provided gravity is ignored.

If you do not intend to ignore gravity, remember that gravity exerts a force of 9.8 N (g) at the surface of the Earth.
 
  • #3
I am and idot, thanks for the gravity tip also ther is a diagram I did not provide taht is very important, just out of curiosity do you put pictures on here using HTML type.

Calculation is
-980 + 3t=100kg*.2
3t=-20+980
t=320 N
The reason it is 3t is because the diagram shows the rope connecting the celling and the platform/man 3 times with the two pullys)
 
  • #4
30
0
I am and idot, thanks for the gravity tip also ther is a diagram I did not provide taht is very important, just out of curiosity do you put pictures on here using HTML type.

Calculation is
-980 + 3t=100kg*.2
3t=-20+980
t=320 N
The reason it is 3t is because the diagram shows the rope connecting the celling and the platform/man 3 times with the two pullys)
I believe HTML is disabled, although you could upload the image and use IMG tags, I believe.
 

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