Who calculated the correct diameter for axial deflection using 6000lb force?

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    Axial Deflection
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Discussion Overview

The discussion revolves around the calculation of the correct diameter for axial deflection under a specified force of 6000 lb. Participants are examining their approaches to solving the problem, including the forces considered and the resulting diameters calculated. The scope includes homework-related calculations and technical reasoning regarding axial forces and deflection.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant calculated a diameter of 3.668 inches by subtracting 1500 lb from 6000 lb for the force, while another participant calculated a diameter of 2.117 inches using the full 6000 lb as the force.
  • A third participant suggests that neither of the initial calculations is correct and emphasizes the importance of drawing free body diagrams to analyze the problem accurately.
  • Another participant questions the diameter of rod BC being greater than that of rod AB, suggesting a potential inconsistency with the problem's illustration.
  • One participant proposes a diameter of 2.445 inches, indicating a different calculation approach.
  • Another participant highlights the need to determine whether the axial forces involved are tensile or compressive, which may affect the calculations.

Areas of Agreement / Disagreement

Participants do not appear to agree on the correct diameter, with multiple competing views and calculations presented. The discussion remains unresolved regarding which calculation is correct.

Contextual Notes

Participants have not reached consensus on the assumptions regarding the forces acting on the rods, the definitions of tensile versus compressive forces, and the implications of their free body diagrams.

tsukuba
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Homework Statement


I was able to come up with an answer but I am not sure if its right.
I get the value of 3.668 in for diameter and my friend gets 2.117 in.
I get that value because I subtracted 1500 lb from 6000lb to get my force while he used 6000lb as his Force
Who is right and why?
Thank you

IMG_20141207_123906.jpg


Homework Equations



S= F L / A E

The Attempt at a Solution


First I calculated the deflection in SAB and I got 0.00189 in.
then I calculate SBS
I rearrange the formula to solve for A
For my Force I take 1500lb and subtract 6000
At the end I get a Diameter of 3.668 in.
 
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My calculations don't agree with either of you. In order to analyze this problem properly, you should draw free body diagrams of each rod.

According to your calculations, the diameter of rod BC should be greater than the diameter of rod AB, which is certainly not implied by the figure illustrating the problem.
 
this is how I drew my FBD and that's how I got my Forces
output.jpg
 
Is the answer 2.445 inches?
 
It's also important to know if the axial forces are tensile or compressive.
 

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