High Quality Content by WIKIPEDIA articles! In the systems sciences the term system equivalence is the notion that a parameter or component of a system behaves in a similar way as a parameter or component of a different system. Similarity means that mathematically the parameters/components will be indistinguishable from each other. Equivalence can be very useful in understanding how complex systems work. Examples of equivalent systems are first- and second-order mechanical, electrical, torsional, fluidic, and caloric systems. Equivalent systems are mostly used to change large and expensive mechanical, thermal, and fluid systems into a simple, cheaper electrical system. Then the electrical system can be analyzed to validate that the system dynamics will work as designed. This is a preliminary inexpensive way for engineers to test that their complex system performs the way they are expecting.