Finding the Coordinates of Point A in a Force Equilibrium System

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Homework Help Overview

The discussion revolves around determining the coordinates of point A in a force equilibrium system. The original poster describes a scenario where the system is in equilibrium, involving forces acting in both the x and y directions, with specific weights and tensions in ropes influencing the setup.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the equilibrium conditions and the implications of equal tensions in the ropes. There are attempts to resolve forces into components and relate angles to the tensions. Questions arise about the angles formed by the ropes and their relationship to the forces acting on point A.

Discussion Status

Some participants have provided insights into the relationships between the angles and tensions, suggesting that the angles may be equal. There is ongoing exploration of how to express the coordinates in terms of the angles and other variables, but no consensus has been reached on the correctness of the reasoning or the final expressions.

Contextual Notes

Participants are working under the assumption that the tensions are equal and that the system is in equilibrium, but there are hints about additional geometric considerations that may not be fully resolved.

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Homework Statement


The system is in equilibrium. What are the coordinates of point A?
(see attached image)


Homework Equations


ƩF_y = 0
ƩF_x = 0

The Attempt at a Solution


The sum of forces in the x and y directions is zero since the system is in equilibrium. At point A, I also know that there is a weight W directed downwards, and each of the two tensions in the ropes T are equal in magnitude.

I was told that this "proof" problem required consideration of the distance between the weight on the left and its pulley (call it ε), and also the two angles (α and β) between each of the two ropes at point A with the horizontal.

Although I was given these hints, I still can't figure out where to start in the problem. Can anyone help me out here? Thanks!
 

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Actually all the tension of the strings are equal.
Using these values, you can find the angles by resolving the components.
 
Nivlac2425 said:

Homework Statement


The system is in equilibrium. What are the coordinates of point A?
(see attached image)


Homework Equations


ƩF_y = 0
ƩF_x = 0

The Attempt at a Solution


The sum of forces in the x and y directions is zero since the system is in equilibrium. At point A, I also know that there is a weight W directed downwards, and each of the two tensions in the ropes T are equal in magnitude.

I was told that this "proof" problem required consideration of the distance between the weight on the left and its pulley (call it ε), and also the two angles (α and β) between each of the two ropes at point A with the horizontal.

Although I was given these hints, I still can't figure out where to start in the problem. Can anyone help me out here? Thanks!
attachment.php?attachmentid=45987&d=1333848177.jpg


What is the tension in each of the three ropes ?
 
SammyS said:
What is the tension in each of the three ropes ?

I believe the tensions are equal and they are all equal to W
 
Nivlac2425 said:
I believe the tensions are equal and they are all equal to W
Correct.

What does that tell you about the angles made by the three ropes at point A ?
 
SammyS said:
Correct.

What does that tell you about the angles made by the three ropes at point A ?

So if I resolve the tensions into their components, and realize that the sum of forces in x and y are both equal to zero, I get the following relations:

sin(α) + sin(β) = 1

cos(α)=cos(β)

This tells me that the angles must be equal, and that α = β = 30°

And since: tan(α) = (h+y)/(b-x) and tan(β) = y/x,

I get x = (1/2)[b - hcot(30°)] and y = (1/2)[btan(30°) - h]

Is this the correct way to think about the problem?
 

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