Free-Body Diagrams and Bogus Work

• Autores: William H. Bassichis
• Localización: The Physics Teacher, ISSN 0031-921X, Vol. 62, Nº. 5, 2024, págs. 342-345
• Idioma: inglés
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• Resumen

  • There are currently two quite different approaches to the introductory, calculus-based course for engineering students. The traditional course is strictly mechanics, while the newer, energy-first course, is based on thermodynamics. Part of the early impetus for this change was the perceived student confusion arising from the use of a quantity called pseudowork. This quantity uses the external force acting on an object and, as such, is intimately connected to the free-body diagram (FBD). In the energy approach, a force may act on a body but does no work, in the thermodynamic sense, depending on the displacement of the point of contact. That force would then not appear explicitly in the solution. There is a resulting significant difference in the importance of the FBD in the two approaches. A correct FBD can guide the student in determining which fundamental law should be used to solve a problem.