What is the unit of pressure in the SI system?

• A. Atmosphere
• B. Pascal (Pa)
• C. Bar
• D. Millimeter of Mercury

Answer: (B)

The unit of pressure in the SI system is the Pascal (Pa). The Pascal is defined as one newton per square meter, which represents the force of one newton acting over an area of one square meter. This unit is fundamental in physics and engineering because it allows for the measurement of pressure in a standardized manner, applicable in various scientific fields.

While other units of pressure, such as the atmosphere, bar, and millimeter of mercury, are commonly used in specific contexts or regions, they are not the primary SI unit. For instance, an atmosphere is a unit based on a defined standard (approximately equal to 101,325 Pa), and a bar is also a metric pressure unit equal to 100,000 Pa. Millimeters of mercury are often used in medical and meteorological settings, but they can be converted to Pascals, making the Pascal the definitive SI unit for pressure.