Finding Tension in Cables: How to Use Moments to Solve for Unknowns

  • Thread starter Thread starter Nanart
  • Start date Start date
  • Tags Tags
    Cables Tension
Click For Summary

Homework Help Overview

The discussion revolves around determining the tension in cables using moments in a static equilibrium problem involving a sign and forces acting on it. Participants are exploring the mechanics of forces and moments in a physics context.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation, Assumption checking

Approaches and Questions Raised

  • Participants suggest starting with free body diagrams and summing forces and moments. There are attempts to clarify the role of the center of gravity and the distribution of forces. Some express uncertainty about the initial steps and seek further guidance on the approach.

Discussion Status

There is an ongoing exploration of different methods to analyze the problem, with some participants suggesting breaking the system into separate components while others propose a more holistic approach. No consensus has been reached, but several productive directions have been offered.

Contextual Notes

Some participants question the accuracy of the problem statement and the assumptions regarding the forces acting on the cables, indicating potential discrepancies in the setup.

Nanart
Messages
13
Reaction score
0

Homework Statement



pysicssign.jpg




Obviously the picture is not to scale

The Attempt at a Solution


I really have no ides where to start I assume you have to use moments to find the tension in each cable but I am really not sure how to go at it.
I think the 20 N force hanging from the sign would only act through the one cable and wouldn't effect the other cable because it is the same distance from the end as the support cable.

Thanks for the help
 
Physics news on Phys.org
Start off by drawing your free body diagram. Since the material has a constant density its CG will act at the center of the sign. Next, you find the sum of the forces in the y direction. Also you are correct in saying that you can sum the moments. Just one pointer, try finding the point with most forces acting at it.
 
djeitnstine said:
Start off by drawing your free body diagram. Since the material has a constant density its CG will act at the center of the sign. Next, you find the sum of the forces in the y direction. Also you are correct in saying that you can sum the moments. Just one pointer, try finding the point with most forces acting at it.

I really still don't know where to start can someone go over the steps in doing this question
Thanks
 
Break the figure apart and treat each body as a separate FBD. Show the forces acting on that body and then start writing your equations.
 
Dr.D said:
Break the figure apart and treat each body as a separate FBD. Show the forces acting on that body and then start writing your equations.

Hmm that is too much work, he can do this using 2 equations by treating the whole thing as one object and analyze the tension in the cables alone.
It seems he wants us to do it for him but if he could just separate the body from the wall, then sum the forces in the y direction, and sum the moments (or torques) about either the point where Ta or Tb is acting then he is done.
 
Last edited:
A little bit of discovery is a wonderful learning experience.
 
Haha, i'll place it as a spoiler then ;)
 
The problem statement is incorrect, based on the dimensions shown. One of the rods will not be in tension.
 

Similar threads

  • · Replies 19 ·
Replies
19
Views
3K
  • · Replies 10 ·
Replies
10
Views
6K
Replies
14
Views
3K
  • · Replies 2 ·
Replies
2
Views
13K
  • · Replies 31 ·
2
Replies
31
Views
5K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 9 ·
Replies
9
Views
4K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
19
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K