How is pressure defined in relation to area?

Pressure is defined as the force applied per unit area. In the context of measuring pressure, using pounds per square inch (psi) is the most common and practical method for various applications, such as tire pressure, hydraulic systems, and more. This unit expresses how many pounds of force are exerted over one square inch of surface area, providing a clear understanding of how much force is distributed across that area.

The other units mentioned are not directly applicable to the definition of pressure in the same manner. Pounds per square foot, for instance, would denote a different scale but is less common for pressure measurement, especially in smaller areas. Pounds per gallon and pounds per cubic foot are units of weight per volume, not pressure, and do not account for the area over which the force is applied. Thus, pounds per square inch effectively captures the essence of pressure in both practical use and scientific understanding.