Pressure is the force acting normally on a surface divided by the area of that surface. In symbols, P = F ÷ A, where pressure P is in pascals (Pa), force F is in newtons (N) and area A is in square metres (m2). One pascal is one newton per square metre, so 1 Pa = 1 N/m2.
Example: a crate pushes down with a force of 600 N on a floor area of 0.50 m2. The pressure is 600 ÷ 0.50 = 1200 Pa.
The equation can be rearranged to F = P × A and A = F ÷ P. If a force of 300 N acts at a pressure of 1500 Pa, the area is 300 ÷ 1500 = 0.20 m2. A pressure of 2000 Pa on an area of 0.05 m2 gives a force of 2000 × 0.05 = 100 N.
Watch the units. Areas are often given in cm2 but the equation needs m2. There are 10 000 cm2 in 1 m2, so 500 cm2 is 0.05 m2. A force of 200 N on 500 cm2 gives 200 ÷ 0.05 = 4000 Pa.