title: Thermal Physics: Kinetic Theory, Thermodynamics and Statistical mechanics
author: Dr. S C Garg
description: "S. C. Garg, PhD (University of Delhi), is Professor of Physics at School of Sciences, Indira Gandhi National Open University (IGNOU), New Delhi. Earlier he was Pro Vice Chancellor of IGNOU and Founder Director of Centre for Learning and Teaching, National University of Lesotho, Roma, Southern Africa. Before joining IGNOU in 1989, he was with the Department of Physics, Hindu College, University of Delhi for about 12 years. With more than three decades of teaching experience in India and abroad, Prof. Garg has co-authored four textbooks in physics at the undergraduate and Masters levels. He has published several research papers in national and international journals and guided several students for their PhD degree. Having been a member of academic councils and management boards of several universities in the India and abroad, he has wide experience in planning and development of curricula and learning materials for different groups of learners. His areas of research are Theoretical Reactor Physics and Physics Education. R. M. Bansal, PhD (University of Delhi), is Associate Professor, Department of Physics, Hans Raj College, University of Delhi. He has more than three decades of teaching experience and has been a member of several committees tasked to revise physics courses. His areas of research are Theoretical Solid State Physics and Neutron Transport. C. K. Ghosh, PhD (University of Calcutta), is Director, National Centre for Innovations in Distance Education, Indira Gandhi National Open University (IGNOU), New Delhi. He has held several important positions in Student Support Services Division of IGNOU. Before joining IGNOU in 1989, he was with the Department of Physics, Scottish Church College, Kolkata. He has been the nodal officer of the Integrated MSc-PhD programme in physics and astrophysics under IGNOU-IIA collaboration. He has co-authored two books in physics and published several research papers. "
zlib_text: Chapter 18 
   
   
  Page 1 
  CHAPTER 18 – Kinetic Theory of Gases 
   
  1. 
  (a) The average kinetic energy depends on the temperature: 
   
   
   
  !mvrms2 = *kT = *(1.38 × 10–23 J/K)(273 K) =        5.65 × 10–21 J. 
   
  (b) For the total translational kinetic energy we have 
   
   
   
  K 
  = N(!mvrms2) = *nNAkT  
   
   
   
   
  = *(2.0 mol)(6.02 × 1023 molecules/mol)(1.38 × 10–23 J/K)(293 K) =        7.3 × 103 J. 
   
  2. 
  The average kinetic energy depends on the temperature: 
   
   
  !mvrms2 = *kT, which gives 
   
   
  vrms = (3kT/m)1/2  = [3(1.38 × 10–23 J/K)(6000 K)/(4 u)(1.66 × 10–27 kg/u)]1/2 =       6.1 × 103 m/s. 
   
  3. 
  The average kinetic energy depends on the temperature: 
   
   
  !mvrms2 = *kT. 
   
  If we form the ratio for the two temperatures, we have 
   
   
  (vrms2/vrms1)2 = T2/T1 = 373 K/273 K, which gives vrms2/vrms1 =       1.17. 
   
  4. 
  The average kinetic energy depends on the temperature: 
   
   
  !mvrms2 = *kT.  
   
  We form the ratio at the two temperatures: 
   
   
  (vrms2/vrms1)2 = T2/T1 ; 
   
   
  (2)2 = T2/293 K, which gi