### What are the four fundamental variables in aerodynamics?

The four fundamental quantities in language of aerodynamics are Pressure, Density, Temperature and Velocity. Let us look at each one.

Pressure:

Pressure is defined as a point property. It varies from one point to another on the surface of the object. (or) Pressure is defined as force per unit area, e.g., newton’s/meter2

Detail explanation:

In fact, pressure is usually defined at a point on the surface can vary from one point to another point. we can use the language of differential calculus to see this more clearly.

Consider a point B in a volume of gas. Let

dA = incremental area around B

df = force in perpendicular

then the pressure at point B in the gas define as

$p\left(pressure\right)=lim\left(dF/dA\right)$

Pressure is a one of most fundamental and important variable in aerodynamics. Common units of pressure are Newton/meter2, dynes/centimetre2, pound/foot2 and atmospheres. Abbreviations for this quantities are N/m2 , dyn/cm2, lb/ft2, and atm, respectively.

In the next article we will discuss about the Density