The roof truss of a warehouse can be represented by the planar pin-jointed truss in Figure 2. Wind load can be represented by a horizontal point load at E, and the load from a crane supported on the truss by a vertical load, initially at J. (a) A vertical load of 30 kN is applied at J and a horizontal load of 20 kN is applied at E, as shown in Figure 2. i) Calculate the support reactions at K and F. ii) Find the force in bar CG and state whether it is in tension or compression. (b) The 30 kN vertical load can now move between nodes J, H and G. The 20 kN load remains in the same location. Bar CG is made of timber with an elastic modulus of 12 GPa, and has a cross sectional area of 3000 mm. i) Calculate the force in CG for each location of the vertical 30 kN load. ii) What is the change of length of CG as the vertical load is moved from J to G? A 2m 2m K B J H C D 30KN Figure 2: Planar truss for analysis. E F 77777 20KN