热力学热物理学(Thermodynamics).doc

热力学：热物理学：(Thermodynamics) 何谓热力、热物理学→我以为是最人性化的一支物理与自然界最有密切关连。 Classical Physics have three branches： Mechanics－Dynamics of particles acted upon by forces Newtons law.(Lagrange. Hamilton Principle) E.M. Theory－Dynamics of fields that mediate those forces Maxwell equations. Thermodynamics－Apply to all Types of systems in macroscopic aggregation. It does not predict specific numerical values for observable quantities, but It sets limits (inequalities) on permissible physical processes, also establishes relationships between (among) apparently unrelated properties. Thermodynamics： 与其它物理最大的不同在于其可以应用至任何系统，it is not based on a new and particular law of nature, it only reflects a commonalty or universal feature of all Laws. Thermodynamic SystemMacroscopic System: Thermodynamics describes only (static states, equilibrium) of macroscopic system. 问：人可以看到的最小空间是多小?? 在力学中每一个粒需要三个空间作标来描述，但109个粒子，其运动状态能否用力学的坐标来描述呢??答案是相当困难，即使是最近流行的用计算机仿真(以牛顿运动定律为基础的Molecular Simulations)至多也祗可以模拟几百个粒子的运动。这个的系统就是一个巨观的系统，就必须用热力学的坐标来描述。 问：What is the smallest time interval can be detected by man ?? ～10-2sec 或10-1sec之间。而原子振动的周期～10-15sec，所以可以测得的值基本上是一种时间上的平均值，例如压力，......。 Macroscopic coordinates are time-independent, they are time average and spatial average. 根据上述讨论我们可以给出一个所谓的热力学系统的完整定义: Thermodynamic system : Macroscopically homogeneous, isotropic and uncharged, that are large enough so that surface effects can be neglected, and that are not acted on by electric, magnetic and gravitational fields. 且此系统仍然遵守基本物理定律：能量守恒定律。热力学系统中所讨论的热力能量(如化学位能、内能、自由能等)，多半只有他们的差值才具有物理义意(如第一定律)，或是关系式，如热力学的Maxwell equations 就是一个很好的例证。 Macroscopic Coordinates is 1: They involve no special assumptions concerning the structure of matter. 2: They are few in number. 3: They are suggested more or less directly by our sense perceptions. 4: They can generally be directly measured. 问: 什么是热平衡(Thermal equilibrium) 热力学第零定律： a与b分别与c达成热平衡，则a和b也达成热平衡 温度的定义：若A和B成热平衡，(thermal equilibrium)，则A和B有相同的温度。比较Logic的说法是： 系统的温度是一种性