Pulleys and block-and-tackles are often used to hoist objects into the upper levels of barns and garages. the supports that hold these contraptions come in various forms. let us model the illustrated orange support as a planar truss with horizontal member ac that is subjected to the vertical tension load t . given the following: t= 90 n ab=100 cm ac 140 cm ? =25. determine forces f_ab, f_ac, and f_bc in n in members ab, ac, and bc.