Pascal’s Law: Applications & Examples
Pascal’s Law states that the pressure applied to a fluid in a closed container is transmitted equally
to all points in the fluid and act in all directions of the container. Pascal’s Law is applicable to
both solids and liquids.
When a fluid is at rest, the same amount of pressure is applied at all the points which are at the
same height. Therefore, it can rightly be said that since the liquid does not flow, it definitely has
equal pressure acting on it at all the points.
The mathematical representation of the law is as follows:
F = PA; where F=applied force, P=pressure transmitted, and A=cross-sectional area.
Let us have a look at some of the examples of Pascal’s Law:
1. Hydraulic Lift
A hydraulic lift is versatile in its utility. It has a hydraulic apparatus which is used to lift heavy
objects. In the case of hydraulic lifts, force applied creates “lift” and “work.”
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It is based on the principle of equal pressure transmission throughout the fluid. A narrow cylinder
(A) is connected to a wider cylinder (B) fitted with airtight pistons filled with an incompressible
fluid. The mathematical representation of the Pascal’s Law helps in the determination of pressure
which can be exerted on the fluid in the piston so as to create enough force for lifting and moving
an object.
When pressure from piston A is transmitted to piston B, piston B lifts the heavy object like big
machines, vehicles. The hydraulic lift technology has widespread applications in the industrial,
construction, transport sector, etc.
2. Hydraulic Jack
Hydraulic jacks, which come under the category of a closed container, follow the principle of
Pascal’s Law. They are used to lift heavy bodies.
The hydraulic jack consists of two cylinders, a larger and a smaller one; and these two cylinders
are connected. When its handle is pressed down, a valve closes and the small piston forces the
fluid through another valve to a larger cylinder which, then, produces a large force to be
transmitted to the load. Therefore, we can say that when force is applied, the pressure is exerted
throughout the volume and surface of the cylinder.
The handle is moved up and down repeatedly until the load is sufficiently lifted up by the
hydraulic fluid flowing buffer tank to the small cylinder. Hydraulic jacks are highly
advantageous in the automotive industry and are often used to lift cars above the ground level
for repair and maintenance.
3. Hydraulic Brakes
One of the most common examples of Pascal’s Law is the hydraulic braking system present in the
automobiles. Every time you see a car come to a halt; the principle of Pascal’s Law comes into
action.
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A number of components form the braking system in cars. When force is applied on the brake
pedal, there is a movement of the piston and rod in the master cylinder. A liquid which is known
as brake or hydraulic fluid, enclosed in the container, is used to transmit the pressure from the
brake pedal to the wheels of the vehicle against the brake discs or brake drums. The frictional
force between these force components causes the vehicle to stop. Hydraulic brakes are used in
cars, motorcycles and lorries.
Example:
1. A pressure of 2000 Pa is transmitted throughout a liquid column due to a force being
applied on a piston. If the piston has an area of 0.1 m2, what force is applied?
This can be calculated using Pascal’s Law formula.
F = PA
Here,
P = 2000 Pa = N/m2
A = 0.1 m2
Substituting values, we arrive at F = 200 N
