MecMovies 4.0 : M1.4: Load Capacity of Two-Bar Assembly

Begin by considering the equilibrium of joint $B$ , noting that members (1) and (2) are two-force members. Two equilibrium equations, $\underset{}{\sum F_{x} = 0}$ and $\underset{}{\sum F_{y} = 0}$ , can be written for the forces acting at joint $B$ .

The two equilibrium equations contain three unknown forces: $F_{1}$ , $F_{2}$ , and $P$ . Three unknown forces cannot be determined from just two equations; therefore, additional information must be incorporated to solve the problem.

The figure shows a diagonal member labeled 1 and a horizontal
member labeled fixed to a column on the right at the points A on top and C below. The diagonal member runs between
points A and B and the horizontal member runs between the points B and C. Joint B is at a distance of 4.3 meters
to the left of A and 5 meters below A. Joint C is at a distance of 7 meters directly below A. The load at joint B is
labeled P and it is directed downwards.