Pounds per Square Inch (PSI) is a unit that measures what?

Pounds per Square Inch (PSI) is a unit that is specifically used to measure pressure. Pressure is defined as the force applied per unit area. In the case of PSI, it quantifies how much force is exerted on a given area in pounds. For example, when air is pumped into a tire, the pressure measured in PSI reflects how much air is forced into the tire's interior, thus illustrating the relationship between force and area. This makes PSI an essential unit in various fields, including engineering and mechanics, where understanding pressure levels is crucial for safety and performance optimizations.