What does stress measure in a structural member?

Stress measures the internal forces within a structural member that develop as a reaction to an external load. It is quantified as the load acting on the structural member divided by its cross-sectional area. This relationship is fundamental to understanding how materials respond to forces, as stress indicates how much load a material can handle relative to its size.

The correct answer emphasizes that stress is not just about the total load but specifically how that load is distributed across a specific area, allowing engineers and designers to evaluate whether materials are suitable for particular applications and how they will behave under various loading conditions. Understanding this concept is crucial for ensuring safety and structural integrity in design.