Help with Statics Problem | Shaun

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The discussion revolves around a statics problem involving static equilibrium with three unknowns and corresponding equations for force and torque. Participants suggest starting with the torque equation to find tension (T) and then using it to solve for other forces. A key misunderstanding arises regarding the weight of the beam, where one participant mistakenly calculates the weight using incorrect units. After clarification, it is revealed that the beam's weight is given in pounds, not in Newtons, leading to a realization of the error. The conversation emphasizes the importance of unit consistency in solving physics problems.
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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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