At the end of this section you should be able to:

1. Recognize a problem as a “Frames & Machines”-type problem versus truss of simple rigid body

2. Properly create FBDs for multi-body systems with internal and external forces

3. Identify two-force members in a system by inspection

This section focuses on frames and machines, where multiple rigid bodies interact through internal connections and must be solved as a multi-body equilibrium system. You will learn to recognize when a problem is a frames-and-machines problem (not a truss or a single rigid body), draw correct free body diagrams for each member and for the overall assembly, and track internal versus external forces without double counting. You will also identify two-force members by inspection and use that insight to simplify unknown reactions. Practice covers common statics connections and mechanisms such as pins, rollers, collars, rocker supports, peg-and-slot joints, pulley interactions, and compound members where more than two bodies meet at a joint. Mathematica resources are included to help set up and solve the resulting equilibrium equations.