States of Matter Pressure Pressure is a commonly used word. It is applied to psychological stress and mechanical conditions.
Pressure has a very specific meaning in chemistry.
It is defined as force divided by area. Pounds per square inch is a pressure unit that literally states the definition. PSI labels are visible on inflated objects like basket balls, inflated boats and car tires. When you stand on the floor, you exert a force against the floor. The pressure you exert is your body weight in pounds divided by the surface area under your feet or shoes.