### 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/meter^{2}

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

$p\left(pressure\right)=lim(dF/dA)$Pressure is a one of most fundamental and important variable in aerodynamics. Common units of pressure are Newton/meter^{2}, dynes/centimetre^{2}, pound/foot^{2} and atmospheres. Abbreviations for this quantities are N/m^{2} , dyn/cm^{2}, lb/ft^{2}, and atm, respectively.

In the next article we will discuss about the Density