1. **Problem Statement:** Determine the force in each member of the truss given loads $P_1 = 6$ kN and $P_2 = 9$ kN, and state whether each member is in tension or compression.
2. **Assumptions and Method:** We use the method of joints or sections to analyze the truss. Each joint must satisfy equilibrium: $$\sum F_x = 0, \quad \sum F_y = 0.$$ Members in tension pull away from the joint, members in compression push towards the joint.
3. **Step 1: Calculate support reactions.** Sum moments about one support to find vertical reactions. For example, if the truss is simply supported, use:
$$\sum M_A = 0 \Rightarrow R_B = \frac{P_1 \times d_1 + P_2 \times d_2}{L}$$
where $d_1, d_2$ are distances from support A to loads, and $L$ is the total length.
4. **Step 2: Analyze each joint starting from supports.** At each joint, write equilibrium equations:
$$\sum F_x = 0, \quad \sum F_y = 0$$
Solve for unknown member forces.
5. **Step 3: Determine tension or compression.** If the force direction assumed is away from the joint and the calculated force is positive, the member is in tension. If negative, it is in compression.
6. **Example:** Suppose member AB is horizontal and member AC is diagonal. At joint A:
$$\sum F_x = 0: F_{AB} - \text{horizontal component of } F_{AC} = 0$$
$$\sum F_y = 0: R_A - P_1 - \text{vertical component of } F_{AC} = 0$$
Solve these for $F_{AB}$ and $F_{AC}$.
7. **Repeat for all joints** until all member forces are found.
8. **Final answer:** List each member with its force magnitude and state "tension" or "compression" based on sign.
*Note:* Without the truss geometry and member layout, exact numeric answers cannot be provided here. Please provide a diagram or member lengths and angles for precise calculation.
Truss Force Analysis 401965
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