[Statics] Finding the Tension

  • Thread starter Ortix
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  • #1
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Homework Statement


[PLAIN]http://img830.imageshack.us/img830/1091/unled2cjt.jpg [Broken]


Homework Equations


I used sum of forces in x y direction and sum of moments


The Attempt at a Solution



So my problem here is that I solved for Ay (1275.3N) and now I have to solve for T

The obvious approach would be to use sum of forces in x direction after doing sum of forces in y to find B. Well I did that and found that B = 2550.6 which is double Ay and equal to mg. B is also perpendicular to the bridge thing. Now when I do sum of forces in x direction i do T = Bcos30 but that's wrong apparently.

Which part am I doing wrong? Is my B wrong?

I calculated B like so:
Fy:0 = Ay - mg + Bsin30

Please help :)
 
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Answers and Replies

  • #2
Spinnor
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Does this help? %^)
 

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  • #3
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unfortunately it does not. I figured that much. When i break down the N2 into it's components I still get a wrong answer for T
 
  • #4
998
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i think that it is important to know whether there is friction with the rollers at A and B.
 
  • #5
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There is not, so you would think that the x component of the normal force at B would be equal to T, but it's not!
 
  • #6
998
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If you explain more explicitly how you got B then I can try to give some help.
 
  • #7
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I calculated B like so:
Fy:0 = Ay - mg + Bsin30

Direct copy from my first post... i don't think i can be more explicit than this..
 
  • #8
Spinnor
Gold Member
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There is not, so you would think that the x component of the normal force at B would be equal to T, but it's not!


It has to be. What other forces in the x direction are there?
 
  • #9
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From what I understand there are 2 forces. B and T both pointing in the opposite direction. Is that correct?
 
  • #10
998
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I calculated B like so:
Fy:0 = Ay - mg + Bsin30

Direct copy from my first post... i don't think i can be more explicit than this..

I think that sin must be replaced by cos.
 
  • #11
998
15
From what I understand there are 2 forces. B and T both pointing in the opposite direction. Is that correct?
One must be careful here. The SIN30 component of B is in the opposite direction of T.
 

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