Models

It is a new system that is considerably easier than  the system being modelled, but which saves the important points of the original machine. We might create a physical model of an airplane to check in a wind  tunnel. It does not have additional things; but  it has to have  surfaces  of the correct  shape and size,  in order  to examine the important properties for this purpose.  Mathematical models can take properties of machines that  are important to us, and gives us to discover things  about  the machine much  more conveniently than  by manipulating the original system itself.

One of the hardest things  about  creating models is giving which  aspects  of the original operation to model  and which ones to ignore.  Several classic, dramatic engineering failures may be described to failing to model  important points  of the system.

Another most important dimension in modelling is whether the  model  is calculative or not.     But, of course,  there is likely to be some sort of delay and some error.  We have to check  whether to ignore that delay and error in our model  and work  it as if it were  perfect.Once we have a model,  we may use it in a variety of different aspects.