Final Answer:
1. Force in member bc: 15 kN, in compression.
2. Force in member fc: 10 kN, in tension.
3. Force in member fe: 5 kN, in compression.
Explanation:
Truss analysis involves determining the internal forces within the structural members of a truss, which is crucial for designing and understanding the stability of the structure. In this specific scenario, the force in member bc is found to be 15 kN, indicating compression. This result is derived from the observation that member bc acts as a support, pushing against its joints to maintain equilibrium. Compression forces tend to shorten the member, and in this case, it resists the outward expansion of the joints.
For member fc, the force is determined to be 10 kN, indicating tension. Member fc supports a portion of the external load, and tension forces act to elongate the member, effectively pulling at its joints. Lastly, member fe carries a load and is found to be under compression with a force of 5 kN. As an internal member, it transfers forces within the truss to maintain stability.
Understanding these forces and their nature—compression or tension—is essential for ensuring that each member can adequately support its load without compromising the overall structural integrity. Truss analysis methods, such as the method of joints or sections, are employed to arrive at these force values, providing engineers with valuable insights for designing robust and efficient structures.