A heat engine uses one mole of an ideal monatomic gas as a working substance. The engine can follow either cycle A or cycle B (see the diagram). The ratio of the efficiencies of the cycles is ( e A / e B ) = k . Find both e A and e B .

We received a large number of solutions, not all of them correct, for our October Challenge, Cart Before the Horse. We are pleased to recognize the following contributors:

  • Fernando Ferreira (Universidade da Beira Interior, Covilhã, Portugal)

  • Hratch Barsoumian (Haigazian University, Beirut, Lebanon)

  • Phil Cahill (Lockheed Martin Corporation, North Yorkshire, United Kingdom)

  • Don Easton (Lacombe, Alberta, Canada)

  • Ángel García Rivera, student (Escuela Politécnica Superior, University of Seville, Seville, Spain)

  • Fredrick P. Gram (Cuyahoga Community College, Cleveland, OH)

  • Norge Cruz Hernández (University of Seville, Spain)

  • Gerald E. Hite (TAMUG, Galveston, TX)

  • Harold Houghton...

Supplementary Material

AAPT members receive access to The Physics Teacher and the American Journal of Physics as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.