ABSTRACT
We now begin a detailed and systematic consideration of certain combinations of the basic elements from the mechanical, electrical, fluid, and thermal areas. Since we found analogous behavior quite common when considering elements, we should not be surprised to encounter it also in systems. This commonality allows a great efficiency in our study of system response since knowledge of the characteristics of a particular class of systems is immediately applicable to any member of that class, irrespective of its physical nature. For example, if we once master the step response of a "generic" system, we need never repeat that mathematical work again. Whether a system is mechanical, electrical, fluid, thermal, or mixed will make no difference; their step responses will all follow exactly the same formula if they all belong to the same class. Design techniques learned for one example of a class may be fruitfully carried over to physically different systems of the same class. Every time we encounter a new example of a familiar class, it reinforces our understanding of system behavior and design possibilities.
