复旦大学：《大学物理——热学》课程教学资源（PPT课件）第2次课

大学物理(热学) 金晓峰 复旦大学物理系 xijin@fudan.edu.cn 2006-9-12 2021/9/5

2021/9/5 1 大学物理（热学） 金晓峰 复旦大学物理系 xfjin@fudan.edu.cn 2006-9-12

冷热的感觉

冷热的感觉

伽利略 Galileo galilei 温度计的发明

伽利略 Galileo Galilei 温度计的发明

100°C 212°F 200°F 150°F 50°C -100°F 50°F 0°C 32°F O°F Celsius Fahrenheit (centigrade) FIGURE 17-6 Celsius and Fahrenheit scales compared

Black(1728-1799) By the use of these instruments we have learned. that if we take 1000 or more different kinds of matter such as metals stones. salts. woods. cork. feathers. wool. water and a variety of other fluids although they be at first of different heats, let them be placed together in the same room without a fire

Black（1728—1799) “By the use of these instruments we have learned, that if we take 1000 or more different kinds of matter, such as metals, stones, salts, woods, cork, feathers, wool, water and a variety of other fluids, although they be at first of different heats, let them be placed together in the same room without a fire

and into which the sun does not shine the heat will be communicated from the hotter of these bodies to the colder during some hours perhaps, or the course at a day, at the end of which time, if we apply a thermometer to them all in succession, it will point precisely to the same degree

and into which the sun does not shine, the heat will be communicated from the hotter of these bodies to the colder , during some hours perhaps, or the course at a day, at the end of which time, if we apply a thermometer to them all in succession, it will point precisely to the same degree.

o at Too 叫△L at T FIGURE 17-8 A thin rod of length Lo at temperature To is heated to a new uniform temperature T and acquires length L, where =Eo+△L Linear expansion

E2 (at 2) EI (at T1) FIGURE 17-10 Typical curve of potential energy versus separation of atoms, r, for atoms in a crystal solid (simplified). Note that the midpoint (short vertical line)of the oscillatory motion of atoms is greater at the higher temperature T2

P510° as a function of temperature near w 098 9●9-0 Note the break i ach axis) 096 10910 02468-10 )m2 SECTION 17-4 3

212 9 Basic thermodynamics Jiero-dnaniey to deseribe the new science of heat to which he was to make such major contributions whait 9.3 The first law of thermodynamics Thin ly ern in this section is to describe the content of the first law of thermodynami as possible. My approach has been strongly infuenced by Brian Pippard to t 2leemtx o Cluwslcal Thermmodynemies, which can be warmly recommended forthe of its exposition. 9.3.7 The zeroth law and the definition of empirical temperature To bosin with, we need to establish what is meant by the term empiric/ temperatare ncounter one of the distinctive features of thermodynamic arguments In man we derive the appropriate mathematical structures IFs Let us consider first the thermal properties of fluids, meaning liquids or gases, beens e pressure is isotropic at all points in the fluid and al hape of the containing vessel without changing its volume, so that no work is done. At thin stage, we have no definition of temperature, we now state our first axiom: 是灬兴 It is assumed that the fluid is not subjected to other influences, such as an eleetrie or magnetie field. If the system is wholly defined by twe bulk properties. it is known as a wo-doordinate system. Most of the systems we will deal with are two-coordinnte systems, Notice carefully what this assertion means. Suppose a certain vou r f nuid systeme Then, suppos we ta ke another identica t u n ty p ha win pressure io and volume F wwo neuriuionse to that it alss ends up with coordinates p, and i'. we have asserted that these The constet or systen have been allowed to internet thermalt until atter a very long time no further changes in the bulk properti fluids cannot have arbitrary values for p. F and pa. va and bu n factof experience that two thes t