To make the equation easier to work with, we need to make some assumptions, always being careful to make sure that those assumptions do in fact simplify the equation while not greatly affecting the accuracy of the model.
Always remember that if you are modeling a system (or using a model developed by someone else) make sure you know what all of the assumptions are and check the validity of those assumptions.
In this case we will make four assumptions, which are discussed in detail in the following sections:
These assumptions allow us to reduce the original equation
to the following, more simplified form:
If all of these simplifications make sense already, you may want to
skip ahead to our final simplification.
Otherwise, you may proceed through the explanations.