Pressure is defined as the force being applied perpendicular to the surface of an object per unit area. Pressure is commonly used in describing the force since it is more easy for us to understand it. The units for pressure in SI is Pascal or Newton per square meter and in English units is pounds per square inch. Calculations are as follows:
Pressure = Force / Area
400 Pa = Force / 55 m^2
Force = 22000 Newton