Question: What kinds of precautions did Joule have to make in his measurements such as those depicted in Figure 5-1
Notice that one must be very careful in defining what processes can and cannot happen and idealizations for the systems on which the experiments are being performed. For this reason, historically, a naming convention has arisen for certain types of systems, Definitions
Question: What kind of system is a refrigerator?
Question: What is the universe (i.e., all possible systems that must be considered to conserve energy) for a closed refrigerator plugged into an electrical socket