Bar is a unit of which one of the following?

Bar is a metric unit used to measure pressure [t1][t2]. Pressure is defined as the force applied per unit area [c1][c3]. While the International System of Units (SI) defines the Pascal (Pa) as the standard unit of pressure (where 1 Pa = 1 N/m²), the bar is a widely used practical and meteorological unit [c4][t8]. Specifically, 1 bar is defined as being equal to 100,000 Pascals (100 kPa) [t1][t2]. It is approximately equal to the atmospheric pressure on Earth at sea level [t5][t8]. Meteorologists frequently use the millibar (mb), which is one-thousandth of a bar, to report atmospheric conditions [c2][c5]. In contrast, force is measured in Newtons, energy in Joules, and frequency in Hertz, making pressure the only correct physical quantity associated with the bar [t1][t9].

Sources

1. [1] https://www.nist.gov/blogs/taking-measure/under-pressure-blaise-pascal-barometer-and-bike-tires
2. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 6: Pressure, Winds, Storms, and Cyclones > 6.1 Pressure > p. 82
3. [3] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 6: Pressure, Winds, Storms, and Cyclones > Snapshots > p. 94
4. [4] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 6: Pressure, Winds, Storms, and Cyclones > A step further > p. 87
5. [5] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 23: Pressure Systems and Wind System > 23.1. Atmospheric Pressure > p. 304