Figure 1. Trusses
Figure 1. shows a truss composed of poles. It is stored in fixed bearing A and fixed bearing B. At the nodes N, P and R, forces act as shown in the figure. All joints are torque and friction free.
a) Explain with a sketch, and without calculation, what type of load bar AJ is exposed to (pressure or tension). Indicate any “zero bars” in the truss and show one of them why it is a zero bar. Show whether the truss is internally statically determined or internally statically indeterminate.
b) Calculate the reaction forces (bearing forces) in fixed bearing A and fixed bearing B. Calculate the forces in the rods KM and IL (indicate pressure or tension). Can rod LN be replaced with a rope? Justify the answer.
Task 2
A person at a fitness center holds a weight with mass as shown in figure 2. The exercise machine is fixed clamp E and has a fixed bearing F. You can assume that bolt bearings (joints) A and C, pulleys B and D and fixed bearing F are friction-free. Components: Pulleys B and D, ACD, AE and CF.
A) draw a free body diagram for each of the components of exercise equipment and look at the forces and moments that may act on each component (for the given load).
B) Calculate the friction force (bearing forces and any clamping torque) in E and F For the exercise machine. Indicate the direction of the reactions.
