Smith, Christensen, Mountcastle, and Thompson on entropy, heat engines, and the Carnot cycle

Trevor I. Smith, Warren M. Christensen, Donald B. Mountcastle, and John R. Thompson

Identifying student difficulties with entropy, heat engines, and the Carnot cycle

Phys. Rev. ST Phys. Educ. Res. 11, 020116 – Published 23 September 2015

[This paper is part of the Focused Collection on Upper Division Physics Courses.] We report on several specific student difficulties regarding the second law of thermodynamics in the context of heat engines within upper-division undergraduate thermal physics courses. Data come from ungraded written surveys, graded homework assignments, and videotaped classroom observations of tutorial activities. Written data show that students in these courses do not clearly articulate the connection between the Carnot cycle and the second law after lecture instruction. This result is consistent both within and across student populations. Observation data provide evidence for myriad difficulties related to entropy and heat engines, including students’ struggles in reasoning about situations that are physically impossible and failures to differentiate between differential and net changes of state properties of a system. Results herein may be seen as the application of previously documented difficulties in the context of heat engines, but others are novel and emphasize the subtle and complex nature of cyclic processes and heat engines, which are central to the teaching and learning of thermodynamics and its applications. Moreover, the sophistication of these difficulties is indicative of the more advanced thinking required of students at the upper division, whose developing knowledge and understanding give rise to questions and struggles that are inaccessible to novices.

Smith, Christensen, Thompson on entropy, engines, and cycles

Trevor I. Smith Warren M. Christensen and John R. Thompson
Addressing Student Difficulties with Concepts Related to Entropy, Heat Engines and the Carnot Cycle
AIP Conf. Proc. -- November 5, 2009 -- Volume 1179, pp. 277-280
2009 PHYSICS EDUCATION RESEARCH CONFERENCE; doi:10.1063/1.3266735

We report the rationale behind and preliminary results from a guided-inquiry conceptual worksheet (a.k.a. tutorial) dealing with Carnot's efficiency and the Carnot cycle. The tutorial was administered in an upper-level thermodynamics course at the University of Maine. The tutorial was implemented as the third in a three-tutorial sequence designed to improve students' understanding of entropy and its applications. Initial pre- and post-tutorial assessment data suggest that student understanding of heat engines and the Carnot cycle improved as a result of tutorial instruction