Pascal’s Law states that: Pressure in a fluid at rest is same at all points which are at the same height. A change in pressure applied to an enclosed fluid is transmitted undiminished to every point of the fluid and the walls of the containing vessel.
In this fig, shows an element in the interior of a fluid at rest. Thus, the fluid exerts pressures Pa, Pb and Pc on this element of area corresponding to the normal forces Fa, Fb and Fc as shown in Fig on the faces BEFC, ADFC and ADEB denoted by Aa , Ab and Ac respectively. Then
Hence, the pressure exerted is same in all directions in a fluid at rest. It again reminds us that like other types of stress, the pressure is not a vector quantity. No direction can be assigned to it.
The working of hydraulic lift, hydraulic press and hydraulic brakes are based on Pascal’s law.