In this paper we study a class of physical systems that combine a finite number of mechanical and thermodynamic observables. We call them elementary thermo-mechanical systems (ETMS). We introduce these systems by means of simple examples, and we obtain their (time) evolution equations by using, essentially, the Newton’s laws and the First Law of Thermodynamics only. We show that such equations are similar to those defining certain constrained mechanical systems. From that, and addressing the main aim of the paper, we give a general definition of ETMS, in a variational formalism, as a particular subclass of the Lagrangian higher order constrained systems.

中文翻译：

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基本热机械系统和高阶约束

在本文中，我们研究了一类物理系统，它们结合了有限数量的机械和热力学观测值。我们称它们为基本热机械系统（ETMS）。我们通过简单的示例介绍这些系统，并且本质上仅使用牛顿定律和热力学第一定律来获得它们的（时间）演化方程。我们表明，这些方程类似于定义某些受约束的机械系统的方程。因此，针对本文的主要目的，我们以变式形式形式给出了ETMS的一般定义，将其作为Lagrangian高阶约束系统的特定子类。