申論題

A fluid is held in a container that is covered with a frictionless piston. The container and the piston are thermally insulated (no heat exchange with the environment), and the environn ment is at constant pressure, P. A paddle is placed within the container,which is rotated by dropping a weight of mass M attached to a frictionless pulley contraption (see the figure below). Assume that the mass M drops by a distance h with the gravity g.

You are lucky that the properties of this fluid, including the heat capacities, Cp and Cv,the isobaric thermal expansivity, a, and the isothermal compressibility, B, have all been measured. It also turns out that they are constant for the process of consideration.