Determinate vs Indeterminate Structures - Intro to Structural Analysis

This video defines determinate and indeterminate structural systems, and how to tell the difference.

The unknown reaction forces and internal forces of determinate systems can be solved using only the equations of equilibrium (i.e., statics). Indeterminate systems have more unknowns than can be solved using statics alone, and therefore new structural analysis techniques are required.

The number of unknowns can be counted and compared to the number of equilibrium equations. Examples are shown for how to do this with trusses and frames (or beams, which work the same as frames).