By definition and application, a vector is composed of both magnitude and direction, while a scalar only has a magnitude.
f you look at the application of a force to generate a pressure, you may see that the pressure is always taken as perpendicular to the surface, thus, “direction” is irrelevant and it is a scalar. Pressure is a Force distributed over a unit area, p = F/A.
From the dimensions we see that Force is Newtons (SI) =
While the force is a vector that may affect how it is impacting an area, once we have done the physical averaging of force over area to derive the pressure, there is no longer really a “direction” component to the value.
If you look at a pressure as a force acting on something else, then you are adding a direction component to your pressure magnitude, making it a vector, which of course, is the force.