“The pressure applied to an enclosed fluid is transmitted equally in all directions and acts with equal force on equal areas.”
It’s named after Blaise Pascal, a French mathematician and physicist who first stated this law in 1647.
In simpler terms, this law means that if you press down on one point in a container filled with fluid, the pressure will be distributed evenly throughout the entire fluid.
This law has important practical applications, including in hydraulic systems, where it is used to design machines that use fluid pressure to generate force and motion, such as car lifts and construction equipment.
In summary, Pascal’s law states that pressure applied to an enclosed fluid is transmitted equally in all directions, and is a fundamental concept in the study of fluid mechanics.
Consider a water filled in a glass vessel having holes around its surface. When you apply force through the piston the water rushes out of the holes with the same pressure. The force applied on the piston exerts pressure on water. This pressure is transmitted equally throughout the liquid in all directions. In general, this law holds good for fluids and gases.
A hydraulic machine works on this principle. Hydraulic brakes, car lifts, hydraulic jacks, forklifts, and other machines make use of this principle.
A hydraulic press is made of two pistons connected by a liquid-filled pipe as demonstrated by Pascal’s law.
A force of magnitude F1 is applied to a small piston of surface area A1. The pressure is transmitted through an incompressible liquid to a larger piston of surface area A2. Because the pressure must be the same on both sides.
P = P1 = P2
As we know
P = F/A
F/A = F1/A1= F2/A2
Therefore,
The force F2 is greater than the force F1 by a factor A2/A1.
F2 = A2⁄A1 × F1
By designing a hydraulic press with appropriate areas A1 and A2, a large output force can be applied by means of a small input force. Each side of this equation is the work done by the force. Thus, the work done by F1 on the input piston is equal to the work done by F2 on the output piston. Thus, the principle of conservation of energy applies in the hydraulic press.