What is the SI unit for measuring pressure?

The correct answer is the Pascal, which is the SI unit of pressure defined as one newton per square meter. This unit is widely used in various scientific and engineering contexts, providing a standard measurement for pressure that can be utilized across multiple fields. The Pascal is derived from basic SI units, ensuring that it aligns with the system's overall coherence.

In contrast, while the bar and atmosphere are commonly used units for pressure measurements, they are not part of the SI unit system. The bar is approximately equal to 100,000 pascals, and the atmosphere is defined as being slightly greater than one bar (specifically, 101,325 pascals). The newton is a unit of force rather than pressure, making it irrelevant in this specific context where the focus is strictly on pressure measurement.