Velasco Maíllo, SantiagoFernández Pineda, Cristóbal2023-06-202023-06-202002-090143-080710.1088/0143-0807/23/5/307https://hdl.handle.net/20.500.14352/58863SV thanks the Comisión Interministerial de Ciencia y Tecnología (CICYT) of Spain for financial support under grant nº PB 98-0261 and the Junta de CyL-FSE of Spain for financial support under grant nº SA097/01.A composite system consisting of two identical ideal gases separated by a movable, frictionless, diathermic piston is used to illustrate the application of different extremum principles in thermodynamics. The time evolution of the system from an initial constrained equilibrium state to the final equilibrium state is analysed by means of a very simple phenomenological model.engjournal articlehttp://dx.doi.org/10.1088/0143-0807/23/5/307http://iopscience.iop.org/open access536Termodinámica2213 Termodinámica