1. 25. Pressure 1Last lesson, we embarked on the new topic of Pressure and learnt about different types of pressure, including a few important concepts related to its calculation. Some important pointers: 1. Pressure is defined as Force acting per unit area hence the formula; P = F / A 2. However, to calculate fluid pressure, we use the formula P = hpg, where 2 points in the same liquid at the same level will have the exact same pressure. 3. SI unit for pressure is Pascal (Pa), alternative unit for pressure can be cmHg or mmHg. 4. A measuring instrument called a barometer is used to determine atmospheric pressure by measuring the height of the liquid column in the tube. 5. The higher we go (altitude increases), the lower the atmospheric pressure, so the barometric height will drop.