# 3D statics

1. Jun 24, 2011

### Femme_physics

1. The problem statement, all variables and given/known data

http://img864.imageshack.us/img864/8066/graspcc.jpg [Broken]

the uniform horizontal beam AC, is held at tip A by a circular joint, and at point B it's held by 2 cables, BD and BE, as described in the drawing. At tip C of the beam acts a vertical force, F:

Given

W = 1 [kN]
F = 4 [kN]

Calculate the forces acting on the cables BE and BD and the reaction force at joint A.

Ignore the cables weight.

3. The attempt at a solution

I get stuck at finding T1 and T2, where the 2 eq 2 unknowns cancel each other out

http://img807.imageshack.us/img807/6979/20031xx.jpg [Broken]

http://img842.imageshack.us/img842/4901/20032xx.jpg [Broken]

Last edited by a moderator: May 5, 2017
2. Jun 24, 2011

### cupid.callin

points D,E are in plane of A or something else?
EDIT: ok ... i got it from your solution :)

3. Jun 24, 2011

### I like Serena

Good morning, Fp!

Say, that a sexy problem!

So you have 2 threads keeping that humongous thing up.
But somehow the forces in these 2 threads cancel out?

4. Jun 24, 2011

### Femme_physics

Last edited by a moderator: May 5, 2017
5. Jun 24, 2011

### I like Serena

Did you consider all 3 dimensions?

Otherwise it may yet fall!

6. Jun 24, 2011

### Yuqing

Why not consider a geometrical approach? You have the relative proportions for the tensions in the x,y,z directions. Since you've already solved for one of the components, you can scale for the rest accordingly.

7. Jun 25, 2011

### Femme_physics

Thanks, solved it! And, after that, I solved 5 more 3D statics problem without a hitch! I think I'm getting the hang of it

Yep, always an option thank you.

8. Jun 25, 2011

Good!