Limitations and functions: Four examples of integrating thermodynamics

Physics students are usually unaware of the limitations and functions of related principles, and they tend to adopt "hot formulas" inappropriately. This paper introduces four real-life examples for bridging five principles, from fluids to thermodynamics, including (1) buoyant force, (2) thermal expansion, (3) the ideal-gas law, (4) the 1st law, and (5) kinetic theory. Pedagogically, the examples play the dual roles of demonstrating the limitations (why not) of the prior principles.and highlighting the functions (why) of those principles that follow. Although the examples are not novel, the author enhances the pedagogical value of the existing teaching resources by means of improving visibility, addressing students' prevalent pitfalls, bridging related principles, and increasing the sophistication of the scientific reasoning.