Dimensional homogeneity has been an important consideration in all of the material that has been presented thus far. Clearly, it is necessary that all quantitative relationships be dimensionally consistent and certain conversion factors are often used to achieve this consistency. In this chapter, we will use the principle of dimensional homogeneity in another way. By invoking a formalism to this concept, using dimensional analysis, we will combine important variables that describe a physical situation into a smaller number of dimensional groups.