《大学物理》英文课件20 Entropy and the Second Law of Thermodynamics教程文件.pptVIP

Entropy and the Second Law of Thermodynamics ;Some One-Way Processes irreversible process ;Change in Entropy ;Entropy: - a state function - independent of how that state is reached - only deduced by experiment - prove for a special case – an ideal gas in a reversible process ;Sample Problem;Entropy Change in Process of Free Expansion;Entropy in the Real World: Engines ;A Carnot Engine - an ideal engine ;The work:;Perfect engine:;Carnot Engine Stirling Engine;Sample Problem - Carnot engine, efficiency, power, entropy changes ;Sample Problem - Impossibly efficient engine ;Entropy in the Real World: Refrigerators ;Entropy in the Real World: Refrigerators ;Entropy in the Real World: Refrigerators ;Entropy in the Real World: Refrigerators ;From the second law of thermodynamics: no real engine can have an efficiency greater than that of a Carnot engine when both engines work between the same two temperatures.;A Statistical View of Entropy ;A Statistical View of Entropy ;A Statistical View of Entropy ;Sample Problem;Probability and Entropy ;Sample Problem - Entropy change of free expansion using microstates ;From the Boltzmann’s relation: entropy describes the order of a system, the more order the system is, the smaller the entropy. And conversely the more confusion or chaos, the larger the entropy is.;Homeworks: 16P, 29P, 42E(add probability) ;Homework