Between a Free Adiabatic Expansion and a Quasi-static One

E. N. MIRANDA

Ann Arbor, Michigna, USA

Congreso; 2009 Summer Meeting of the American Asociation of Physics Teachers; 2009

American Asociation of Physics Teachers

In thermodynamics textbooks two adiabatic processes are studied: the free expansion of a gas (Joule experiment) that is a highly irreversible process, and the reversible expansion due to a quasi-static process. We analyze an intermediate situation: the expansion takes place at a high speed, therefore the quasi-static approximation does not hold, but not as high as in a free expansion. In a free expansion the volume changes instantaneously, i.e., with an infinite velocity, while in a quasi-static process the volume change velocity is almost zero. We will find a parameter r that describes the process when the velocity is neither zero nor infinite.