# Line tension

1. May 17, 2010

### drkidd22

I need help trying to figure this problem out.

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2. May 17, 2010

### tiny-tim

Hi drkidd22!

Show us what you've tried, and where you're stuck, and then we'll know how to help!

3. May 17, 2010

### drkidd22

So I have this so far trying to find Tbd.
It will be the same for Tbe as they are the same distance away from A.

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• ###### PhysicsP148.doc
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4. May 17, 2010

### drkidd22

distance on horizontal=√(18^2+18^2)=18*√2 ft
distance on vertical=21 ft
∴θ=angle in between pole & cable=tan-1(18*√2/21)=50.479 degree
Σall horizontal force=0
1680=2T sinθ
∴T=1088.944 lb
Σall vertical force =0
R=2T cosθ [R= reaction force at A ]
∴R=1385.924 lb

Not sure if it's correct

5. May 17, 2010

### pongo38

How many components are there to the reaction at A (at most)? You ask if it is correct. But you could determine this yourself by recognising that there are at most 6 equilibrium equations for the whole thing.....

6. May 17, 2010

### drkidd22

There are three forces at A
Fx
Fz
Fy

7. May 17, 2010

### pongo38

So have you calculated any of them so far?

(By the way your physicsp148.doc document has just one line and it is sloppy, or incorrect or inconsistent. If T is a force, why do the units have ft at the end?)

8. May 17, 2010

### pongo38

when you say "1680=2T sinθ ", exactly what free body diagram are you considering the equilibrium of?