Learning Goal: To apply the method of sections to a truss and determine the unknown forces in specified members. If a truss is in equilibrium then every member in the truss must also be in equilibrium. This principle is used in analyzing a Part A - Determining the forces in three specified members of the truss truss using the method of sections. To apply the method of sections, we use an imaginary cut through members of the truss to expose the forces in those members as external forces. Determine the forces in members CD, DH, and GH. (Figure 1) If the free-body diagram of the joint on either side of the cut is known, we can apply the equations of equilibrium to that part Express the magnitudes of the forces in pounds to three significant figures. Separate your answers with commas. of the member to determine the forces at the cut section. Since only three equilibrium equations ( F. = 0, _ Fy = 0, View Available Hint(s and _ Mo = 0) can be applied to the free-body diagram of any segment, we should try to select a cut that passes through no more than three members of the truss in which the forces are unknown. Note that the moment equation can be written multiple times, but there are still only 3 independent equilibrium equations available. AEd It vec 0 6 ? For the Howe bridge truss shown, d = 11 ft, Fi = 2950 1b, F2 = 1850 1b, F3 = 2650 lb, and F4 = 3950 1b. (Figure 2) FCD =, FDH =, FGH = 1b, lb, lb Submit Part B - The Sense of the Forces State if the members considered in part A are in tension or compression. Complete each sentence by dragging the appropriate word into the blank. The words can be used more than once. Reset Help compression Member CD is in tension tension Member DH is in compression Member GH is in compression Submit Previous Answers Correct Part C - Determining the forces in three members on the left-hand side of the truss Figure Determine the forces in members HI, BH, and BC. Express the magnitudes of the forces in pounds to three significant figures. Separate your answers with commas. View Available Hint(s) AEd It vec FBC =, FHI =, FBH = lb, 1b, 1b Submit