Adding Value to Force Diagrams: Representing Relative Force Magnitudes

摘要

Nearly all physics instructors recognize the instruc-tional value of force diagrams, and this journal has published several collections of exercises to improve student skill in this area." Yet some instructors worry that too few students perceive the conceptual and problem-solving utility of force diagrams,'" and over recent years a rich variety of approaches has been proposed to add value to force diagrams. Suggestions include strategies for identifying candidate forces,~(6,7) emphasizing the distinction between "contact" and "noncontact" forces,~(5,8) and the use of computer-based tutorials.~(9,10) Instructors have suggested a variety of conventions for constructing force diagrams, including approaches to arrow placement and orientation~(2,11-13) and proposed notations for locating forces or marking action-reaction force pairs.~(8,11,14,15)