UNIVERSITY PHYSICS I CHAPTER 13 Chapter 13 temperature, heat transfer, and first law of thermodynamics Thermodynamics study the thermal energy(often Universe just after called the internal energy) of systems Highest laboratory The central concept of Center of the Sun thermodynamics is temperature Surface of the sun Temperature is one of the% Water freezes seven SI base quantities. Universe today What is temperature? Sense of hot and cold is not/ log/ always reliable 109H--Record low ter
1 Chapter 13 temperature, heat transfer, and first law of thermodynamics Thermodynamics study the thermal energy (often called the internal energy) of systems. The central concept of thermodynamics is temperature. Temperature is one of the seven SI base quantities. What is temperature? Sense of hot and cold is not always reliable
s13.1 Some important concepts 1. The simple thermodynamic system A thermodynamic system is defined as a collection of many particles such as atoms and/or molecules A simple thermodynamic system is a system that is macroscopic, homogeneous, isotropic, uncharged, chemically inert, and experiences no change in its total mechanical energy. The system is sufficiently large that surface effects can be neglect. No electric or magnetic fields are present, and gravitational fields are irrelevant 813.1 Some important concepts 2. Thermal equilibrium Put two system in thermal contact, after long enough time, if their properties(for instance the temperature)do not change, they are in thermal equilibrium. 3. The zeroth law of thermodynamics
2 §13.1 Some important concepts 1. The simple thermodynamic system A thermodynamic system is defined as a collection of many particles such as atoms and/or molecules. A simple thermodynamic system is a system that is macroscopic, homogeneous, isotropic, uncharged, chemically inert, and experiences no change in its total mechanical energy. The system is sufficiently large that surface effects can be neglect. No electric or magnetic fields are present, and gravitational fields are irrelevant. 2. Thermal equilibrium Put two system in thermal contact, after long enough time, if their properties (for instance: the temperature) do not change, they are in thermal equilibrium. 3. The zeroth law of thermodynamics §13.1 Some important concepts
813.1 Some important concepts If body a and b are each in thermal equilibrium with a third body t, then they are in thermal equilibrium with each other. Every body has a property called temperature. When two bodies are in thermal equilibrium we say that they have same temperature And vice versa 4. Temperature There exists a scalar quantity called temperature, which is a property of all thermodynamics systems in equilibrium. Two systems are in thermal equilibrium if and only if their temperatures are equal 813.1 Some important concepts Measuring temperature: ① types of thermometer thermometric property that change with er- By using some physical properties of matte temperature Scale Volume of mercury--common household and laboratory thermometers Constant volume gas thermometer: as shown in Figure
3 If body A and B are each in thermal equilibrium with a third body T, then they are in thermal equilibrium with each other. Every body has a property called temperature. When two bodies are in thermal equilibrium, we say that they have same temperature. And vice versa. 4. Temperature There exists a scalar quantity called temperature, which is a property of all thermodynamics systems in equilibrium. Two systems are in thermal equilibrium if and only if their temperatures are equal. §13.1 Some important concepts Measuring temperature: 1types of thermometer By using some physical properties of matter— thermometric property that change with temperature. Volume of mercury—common household and laboratory thermometers. Constant volume gas thermometer: as shown in Figure §13.1 Some important concepts
813.1 Some important concepts Platinum resistance thermometers--electrical resistance as a thermometric property Thermocouple-different thermal properties of two kind of metal Brass Pointer Helical bimetal 813.1 Some important concepts @Calibrating thermometers (X)=100X-X)(Y)=I 100(Y-Y0 X-X r(X0)=t(X0)=0Ct(X100)=t(X10)=100°C AY)
4 Platinum resistance thermometers—electrical resistance as a thermometric property Thermocouple—different thermal properties of two kind of metal §13.1 Some important concepts 2Calibrating thermometers t X t Y C t X t Y C Y Y Y Y t Y X X X X t X o o ( ) ( ) 0 ( ) ( ) 100 100( ) ( ) 100( ) ( ) 0 0 100 100 100 0 0 100 0 0 = = = = − − = − − = §13.1 Some important concepts
813.1 Some important concepts 3 Ideal gas temperature scale(Kelvin scale) How to avoid the dependence of the particular means or substance? The triple point of water: 0.01C, 1=0K R. Boyle: PV=cons tant J Gay-Lussac: V=vo(1+a,t) J.A. C. Charles: P=Po(1+apt) When P0 a,=ap=a=l/To T=273.l5C s13.1 Some important concepts Experiments: Po oc m P=P(1+apt The intercept of the line on the axis t is 1/ap For all kind of gas, when m is decrease, Po0 a,=a=a=1/T Seale T=273.15°C Gas 1 Gas 3
5 3 Ideal gas temperature scale (Kelvin scale) How to avoid the dependence of the particular means or substance? The triple point of water: t=0.01ºC, T=0K R. Boyle: PV = constant L. J. Gay-Lussac: (1 ) 0 V V t = +α V J. A. C. Charles: (1 ) 0 P P t = +α P When P0Æ0 273.15 C 1/ 0 0 o = = = = T α V α P α T §13.1 Some important concepts For all kind of gas, when m is decrease, P0Æ0. 273.15 C 1/ 0 0 o = = = = T α V α P α T (1 ) 0 P P t P0 ∝ m = +α P The intercept of the line on the axis t is . α P 1/ §13.1 Some important concepts Experiments: 0 100 o t / C P −T0 Gas 1 Gas 2 Gas 3 P0