Complex Pulley System (five different pulleys)

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Homework Help Overview

The problem involves a complex pulley system with multiple pulleys and weights. The original poster is tasked with determining the force needed to maintain equilibrium while considering the weights of the pulleys and the blocks involved.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to calculate the tension in the ropes while initially ignoring the weights of the pulleys. They express uncertainty about how to incorporate the weights of the pulleys into their calculations. Other participants suggest analyzing the tension in each segment of the ropes and applying similar reasoning across different ropes.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem. Some guidance has been offered regarding the calculation of tension in the ropes, but there is no explicit consensus on the final approach to take.

Contextual Notes

Participants are working under the constraints of the problem statement, which includes specific weights for the blocks and pulleys. There is an indication that the original poster may be struggling with foundational concepts related to tension and equilibrium in pulley systems.

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Homework Statement


We are asked to find the force (F) needed to maintain equilibrium. I've drawn a picture; the red, blue, and green ropes are three separate ropes. Block W has a weight of 500 lbs, pulley A has a weight of 10 lbs, and pulley B has a weight of 20 lbs.

the picture: http://img60.imageshack.us/img60/2065/pulleysystem.jpg

Homework Equations


Can't think of any, it seems like this problem just uses some common sense I am clearly lacking.

The Attempt at a Solution



I think I figured out what the answer would be if you ignore the weights of the two pulleys. The tension would be 1/2 W on either side of pulley B, and therefore the tension pulling down on pulley A would be 1/2 W. Therefore, the tension on either side of pulley A would be 1/4 W, and since that rope is the rope to which the force F is applied, F=1/4 W=125 lbs. But I just don't know how to take into account the weights of the pulleys. Thanks for any and all help!
 
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There are three segments in the red rope. Total hanging weight is W+B. Find the tension in each segment. Apply the same thing to green rope.
 
So tension in the red rope would equal 1/3(W+B), and then tension in the green rope would equal 1/3(A+1/3(W+B)) ?
 
Yes.
 

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