What is vacuum? When using the terms ”vacuum”, ”negative pressure”, ”suction”, etc., we mean a pressure that is lower than the atmospheric pressure, which is the pressure of the weight of the air above us. At sea level it is usually 1,013 mbar = 101.3 kPa. 1 Pa equals 1 N/m2 which means that a column of air with a cross-sectional area of 1 m2 presses on the surface of the earth with a force of around 100,000 N. By reducing the pressure in a closed space the atmospheric pressure becomes a potential energy source.
