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ERIC Number: EJ1054998
Record Type: Journal
Publication Date: 2015-Feb
Pages: 2
Abstractor: As Provided
ISSN: ISSN-0031-921X
A Graphical Proof of the Positive Entropy Change in Heat Transfer between Two Objects
Kiatgamolchai, Somchai
Physics Teacher, v53 n2 p95-96 Feb 2015
It is well known that heat transfer between two objects results in a positive change in the total entropy of the two-object system. The second law of thermodynamics states that the entropy change of a naturally irreversible process is positive. In other words, if the entropy change of any process is positive, it can be inferred that such a process is irreversible. Analytic examples such as ice melting, free expansion of gas, and thermal conduction between two fixed-temperature reservoirs are often demonstrated in the introductory classroom, providing convincing evidence of this law. Specific numeric examples can be helpful, but they may not convince talented students wholeheartedly. In this paper, we show graphically via a ln "T-T" curve that the total entropy change due to heat transfer within a two-object system is positive even in the case of unequal masses.
American Association of Physics Teachers. One Physics Ellipse, College Park, MD 20740. Tel: 301-209-3300; Fax: 301-209-0845; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Descriptive
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Grant or Contract Numbers: N/A