The total pressure force on a plane surface is defined as what?

The total pressure force on a plane surface is mainly calculated as the product of the area of the surface and the intensity of pressure acting on it. This relationship is foundational in fluid mechanics, where pressure intensity is defined as force per unit area acting perpendicular to the surface.

When considering a surface submerged in a fluid, the pressure varies with depth due to the weight of the fluid above, and so the average pressure over the area can be determined. Therefore, the total force can be expressed as the average pressure multiplied by the total area.

The other options reflect concepts that are related but do not directly define total pressure force as clearly:

• The area multiplied by the height of fluid relates to the concept of hydrostatic pressure but does not account for the variation in pressure with depth adequately.

• The area multiplied by the density of fluid is useful in determining the weight of the fluid above a certain height (which influences pressure) but does not directly yield the pressure force applied on the surface.

Therefore, the complete picture of how total pressure force is articulated includes the combination of these factors, which is captured by saying all of these represent different aspects contributing to understanding pressure in fluid dynamics.