Help with Statics Problem | Shaun

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Homework Help Overview

The discussion revolves around a statics problem involving static equilibrium, where participants are analyzing forces and torques acting on a system. The original poster seeks assistance with a specific problem from a physics test, indicating a struggle with the calculations and understanding of the concepts involved.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the application of equilibrium equations, including the sum of forces and torques. There are attempts to calculate unknown forces and tensions, with some participants questioning the accuracy of the provided numbers and assumptions about weight.

Discussion Status

The discussion is ongoing, with participants providing guidance on starting points for solving the problem and checking assumptions. There is recognition of potential errors in calculations, particularly regarding the weight of the beam, but no consensus has been reached on the correct approach or solution.

Contextual Notes

Participants note discrepancies in the numbers used for calculations, with some suggesting that the teacher may have made a mistake in the problem setup. There is also a mention of the units used for force, which may be contributing to the confusion.

spatel600
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Please help with this problem:

http://labphysics.uncc.edu/Phys2101/001/Test3A-001-F94.html
#4

Please any help would be greatly appreciated.
AOL SN: spatel600

Please let me know. Thanks. Shaun
 
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This is a straightforward problem in static equilbrium. You have three unknowns, but you can write three equations:
(1) Sum of the vertical components of forces = 0
(2) Sum of the horizontal components of forces = 0
(3) Sum of torques about any axis = 0

Give it a try.
 
I tried that and I got Fx= Tcos() Fy = Fv + Tsin () = mg

Torque = : Lsin (150) T = L/2 (sin 90) mg

I have tried all options and I have been stuck for many hours now. I don't understand. Please help. Thanks
 
Assuming you are using the correct angles, this looks OK to me. What's the problem?

Start with the torque equation. That will allow you to find T. Then use that to find the rest.
 
The numbers do not seem to be right. Everytime I put the answers in the practice test they are incorrect. Give it a try, maybe the teacher made a mistake.
 
spatel600 said:
The numbers do not seem to be right. Everytime I put the answers in the practice test they are incorrect.
Tell me your answers and I'll check them out.
 
My numbers were T= 980 which is 490/sin (150)
Fh = 848.71 which is T cos (30)
Fv = 490 which is mg-Tsin(30)
 
spatel600 said:
My numbers were T= 980 which is 490/sin (150)
Fh = 848.71 which is T cos (30)
Fv = 490 which is mg-Tsin(30)
What units are you using for force?

I'll bet I can guess what you're doing wrong: you are calculating mg as 100x9.8 = 980, right?

If so... oops. The weight of the beam is given as 100 lbs; that means mg = 100 lbs.
 
hahah thanks so much. I can't believe i made that stupid mistake. I really appreiciate all you help. Thanks. Shaun
 

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