# Static equilibrium in 3D

Been working on this problem

http://www.flickr.com/photos/archiphoto77/6179533925 [Broken]
(SEE LINK FOR PHOTO OF PROBLEM)

for quite some time now, and the components don't quite add up for me so im just a tad exasperated... In the x-z projection, I see two forces acting along the x-axis---one being 100cos15 in the -x direction, and the other being Pcos30 in the +x direction. Naturally, all projections of this 3d object should provide equilibrium in all directions. I know that P is equal to 50N, but it just doesnt add up when i take the sum of forces in the xdirection for the x-z projection. Help!

For potential reverse engineering purposes, the solution to the problem is P=50N, Ay=108.8, Cy=58.1 and By=32.4

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rude man
Homework Helper
Gold Member
∑Fx = 0
∑Fy = 0
∑Fz = 0

∑Torques about x axis (thru C) = 0
∑Torques about z axis (thru B) = 0
∑Torques about z axis (thru A) = 0

One of the last two equations may turn out to be redundant.

Anyway, that should give you n equations and n unknowns.