Distinguishing Local Forces from Global State Accessibility: A Pedagogical Clarification Using Buoyancy

Students in introductory and intermediate physics courses often master the calculation of forces while continuing to struggle with conceptual distinctions between equilibrium, stability, and persistence. A recurrent source of confusion arises when global limitations on system behavior are implicitly treated as if they were reducible to local force balances. Using buoyancy as a concrete and familiar example, this article proposes a pedagogical clarification between local forces, which govern instantaneous dynamics, and global state accessibility, which determines which physical states can or cannot be reached. Without introducing new formalism or redefining standard mechanical quantities, the article provides instructors with a conceptual tool to address common student misconceptions related to thresholds, stability, and irreversible loss of accessibility.