What unit is used to measure pressure?

Pressure is defined as the force exerted per unit area. The standard SI unit for pressure is the Pascal (Pa), which is equivalent to one Newton per square meter (N/m²). Hence, when looking at units that relate to pressure, we consider those that express force in relation to area.

The choice mentioning Newtons per mm squared relates to pressure, as it represents the force (in Newtons) distributed over an area measured in square millimeters. This unit is consistent with the definition of pressure and can be converted to Pascals, as there are 1,000,000 mm² in 1 m². Therefore, 1 N/mm² equals 1,000,000 Pa.

In contrast, other choices do not correctly define pressure in relation to standard units. Newtons per square inch and Pascals per cm squared also relate to pressure, but the most recognizable and widely accepted unit in the metric system is the Pascal. Joules per meter squared is a measure of energy per unit area, which is not relevant to pressure. Hence, the understanding of pressure as force per unit area justifies the correct choice of unit as representing Newtons over a specific area measure.