Pascal’s Law

The French scientist Blaise Pascal observed that ‘the pressure in a fluid at rest is the same at all points if they are at the same height’.

1.0Some Important Points Related to Fluid Pressure

(1) Fluid pressure acts in all directions, not just the direction of the applied force. When you inflate a car tire, you are increasing the pressure in the tire. This force acts up, down and sideways in all directions inside the tire.

(2) The fluid pressure at any point on the object is perpendicular to the surface of the object at that point (see figure).

(3) Pressure applied to any part of an enclosed fluid at rest is transmitted in all directions equally to every portion of fluid and the walls of the containing vessel. This is an another statement of Pascal’s law and this property is used in hydraulic press, hydraulic lift
(see figure), hydraulic brakes in cars, trucks. 

Pressure,

$P=\frac{F_1}{A_1}=\frac{F_2}{A_2}or{F}_2=\left(\frac{A_2}{A_1}\right)F_1$

Since, A₂ > > A₁, F₂ > > F₁.

(4) The pressure depends only on the height of the column of fluid above the surface where you measure the pressure. It does not depend on the area of the surface in contact or the shape of the liquid column. The greater the height of the column of fluid above a surface, the greater the pressure exerted by the fluid on the surface. 

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