Due to the different cylinder sizes, this pressure can do work - in this case, supporting the larger weight on the right. In this example, a 500 pound force acting upon a piston with a 2 inch radius creates a pressure of approximately 40 psi. on a confined liquid. The same 40 psi acting upon a piston with a 5 inch radius supports a 3140 pound weight. This is an example of how a liquid in a hydraulic system provides mechanical advantage.
Force is calculated with the formula:
Pressure x Area = Force
40 x [3.14 x (5x5)] = Force
40 x [3.14 x 25] = Force
40 x 78.5 = Force
3140 lbs. = Force
NOTE: Be aware of your units of measure. For example, kilopascals (kPa) and pounds per square inch (psi.) are units of measure for pressure. They can be converted from one unit of measure to another.
(1 psi = 6.895 kPa)
Let’s now practice some Pascal’s Law calculations