What is the unit of pressure used in the SI system?

The unit of pressure in the SI system is the kilopascal. Pressure is defined as force applied per unit area, and the pascal (Pa) is the base unit of pressure in the International System of Units (SI). One pascal is equivalent to one newton per square meter. Since kilopascal is a derived unit, it represents one thousand pascals (1 kPa = 1,000 Pa). This makes it a practical unit used in various applications like meteorology, engineering, and many everyday contexts where pressure measurements are required.

Understanding this context is essential because the other provided units do not correspond to pressure. Kilogram per square meter reflects a density measurement rather than pressure. Kilojoules are a unit of energy, and although dynes can measure force, they do not represent pressure directly without converting to the appropriate area measurement. Thus, the kilopascal is recognized as the standard unit of pressure in the SI system, making it the correct answer.