Coupon Accepted Successfully!


Liquid Pressure in Closed Vessel and Pascals Law

Why does the toothpaste come out through one end of the tube when squeezed at the other end? This happens due to the principle which was first stated in 1652 by the French scientist Blaise Pascal. According to this, for a confined liquid at rest, pressure applied at any point in the liquid is transmitted equally and undiminished in all the directions throughout the liquid.

Consider a liquid with a piston at the top, as in Figure 5.1. Without weight W, let the pressure at A, B and C be P1P2 and P3, respectively. When a weight W = 10 N is placed on the piston of area 2 m2, the additional pressure caused is 5 Nm−2. According to Pascal’s law, the new pressures at AB and C are (P1 + 5), (P2 + 5) and (P3 + 5), respectively, i.e., a pressure of 5 Nm−2 applied at the top is equally transmitted to AB and C or to any other point. Pascal’s law is valid only if the liquid is at rest and is confined.


Description: 59956.png
Figure 5.1 Pascal’s Law


This Pascal’s law is used in hydraulic levers, hydraulic presses, hydraulic jacks and hydraulic brakes.

Test Your Skills Now!
Take a Quiz now
Reviewer Name