2. 3 Models of the fluid: control volumes and fluid particles e Importance to create physical feeling from physical observation e How to make reasonable judgments on difficult problems oIn this chapter, basic equations of aerodynamics will be derived o Philosophical procedure involved with the development of these equations2.3 Models of the fluid: control volumes and fluid particles Importance to create physical feeling from physical observation. How to make reasonable judgments on difficult problems. In this chapter, basic equations of aerodynamics will be derived. Philosophical procedure involved with the development of these equations