Two beams hanging in equilibrium

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Homework Help Overview

The problem involves two identical, uniform beams weighing 260 N each, connected by a friction-less hinge and suspended by vertical wires, forming a "V" shape with a specified angle between the beams. The objective is to determine the force exerted by a crossbar on each beam.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to analyze the problem by breaking it down into components, focusing on one beam and applying equilibrium equations. Some participants question the accuracy of the angles used in the free body diagram and suggest reconsidering the assumptions about force directions.

Discussion Status

Participants are exploring different interpretations of the forces acting on the beams and the crossbar. Some guidance has been offered regarding the nature of the crossbar as a two-force member, prompting the original poster to reconsider their approach based on this understanding.

Contextual Notes

There is mention of a diagram that may not accurately represent the situation, leading to confusion regarding the angles and force directions. The original poster also notes uncertainty about the length of the beam, which affects their calculations.

p0ps1c1e
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Homework Statement


Two identical, uniform beams weighing 260 N each are connected at one end by a friction-less hinge. A light horizontal crossbar attached at the midpoints of the beams maintains an angle of 53 degrees between the beams. The beams are suspended from the ceiling by vertical wires such that they form a "V".

What force does the crossbar exert on each beam?
[/B]
Here is the free body diagram I drew with the symbols I used as well.
http://imgur.com/aFndxKR

Homework Equations


Στ = 0
ΣF = 0

3.
So I thought to break this problem into two and just focus on one of the beams pivoting about point A and then solve for N1. I called the length of the beam L. I feel like I messed up the angles though

Doing that I came up with the equations...
T - mg - N1*sin(53) = 0

T * L cos(37)-mg*(L/2)*cos(37) - N1*(L/2) = 0



Then I thought to solve for N1 but I don't know the length L so I got stuck there


T = mg + N1sin(53) and T = (N1*(L/2) + mg*(L/2)*cos(37)) / L*cos(37)Can somebody give me a hint?
Thanks

 
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p0ps1c1e said:
53 degrees between the beams
This does not match your diagram.

Your diagram also appears to assume the force exerted on a beam by the crossbeam is at right angles to the beam. Any other ideas?
 
The cross bar is a two force member which means that the forces in it act along the length of the bar, not in the directions you have assumed. Try again with this understanding. (Note what happens to the sum of vertical forces on the cross bar with the forces as you have them!)
 
Yeah that sounds right... I originally had it that way but my TA drew it this way. It really confused me haha I'll try it that way and let you all know how it works out
 
I figured it out. Thanks a lot!
 

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