Which one of the following is not the unit of pressure?

Pressure is defined as the force acting per unit area [3]. The SI unit of pressure is the pascal (Pa), which is equivalent to one newton per square meter (N/m²) [1]. Other commonly used units for measuring pressure include the bar, millibar (mb), and atmosphere (atm) [5]. Specifically, 1 bar is equal to 10^5 pascals. In contrast, the joule (J) is the SI unit of energy or work, defined as one newton-meter (N·m). Therefore, J/m² (joules per square meter) represents energy per unit area, which is equivalent to N·m/m² or N/m. This unit corresponds to surface tension rather than pressure. Consequently, while pascal, N/m², and bar are valid units of pressure, J/m² is not.

Sources

1. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 6: Pressure, Winds, Storms, and Cyclones > 6.1 Pressure > p. 82
2. [3] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 6: Pressure, Winds, Storms, and Cyclones > Snapshots > p. 94
3. [1] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 6: Pressure, Winds, Storms, and Cyclones > A step further > p. 87
4. [4] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 23: Pressure Systems and Wind System > 23.1. Atmospheric Pressure > p. 304
5. [5] https://www.sciencedirect.com/topics/mathematics/units-of-pressure