Prof. Bargatin has been developing a number of teaching materials for the classes he teaches at the University of Pennsylvania. In particular, he has developed a number of conceptual questions that are used in the undergraduate course in thermodynamics. Unlike conventional problems that require derivations or numerical calculations, conceptual questions can be answered quickly with none or minimal calculations. While a number of conceptual questions (also known as ConcepTests) have been developed in physics and other fields, there is a shortage of such problems in thermodynamics, especially for mechanical engineers.

Some samples of the conceptual questions from the undergraduate thermodynamics are posted below. The students loved these types of problems, especially when they are discussed interactively in class. If you are teaching thermodynamics and would like to get the suggested answers or additional examples or discuss them with Prof. Bargatin, please contact him by email at bargatin@seas.upenn.edu

  • a closed system (CS)
  • a control volume (CV)
  • could be either CS or CV depending on the problem
  • neither is appropriate for a human being
  • Liquid water will continue to evaporate, i.e., the amount of steam will always increase, the amount of water will decrease (the quality will increase)
  • All steam will eventually condense, so the amount of steam and quality will decrease
  • The amount of steam and quality will remain constant throughout the process
  • 1 cubic inch of water (i.e., a liquid)
  • 1 cubic inch of air (i.e., a gas)
  • No difference
  • Cannot tell/need more information
  • Yes, we can produce heat this way in a sustainable fashion
  • No, because the atmosphere is limited in size and we will run out of it
  • No, because we need to use energy to create vacuum in the first place
  • No because, the heat is very quickly lost to cylinder walls, as discussed last time
  • Relative humidity decreased, absolute increased
  • Relative increased, absolute decreased
  • Both relative and absolute humidity increased
  • Both relative and absolute humidity decreased
  • The exterior side
  • The interior side
  • Equally likely on either side
  • Cannot tell/need more information
  • Only temperature
  • Only relative humidity
  • Only absolute humidity
  • Both temperature and absolute humidity