Test: Pascal's Law - Civil Engineering (CE) MCQ

• Pascal’s principle: Pascal’s Law is the principle of transmission of fluid pressure.
  • It says that "a pressure exerted anywhere in a point of the confined fluid is transmitted equally in all directions throughout the fluid”.
    
• From the above fig., we can see that the force against area within a fluid at rest will always experience pressure perpendicular to its surface area, and the object will experience equal pressure throughout the surface.
• And there are a number of devices, such as hydraulic lifts and hydraulic brakes, that are based on Pascal’s law, these devices used fluids for transmitting pressure.
• From the above explanation we can see that according to Pascal’s law, pressure in a fluid at rest is the same at all points if they are at the same height.
• From the above fig., we can see that the force against area within a fluid at rest will always experience pressure perpendicular to its surface area, and the object will experience equal pressure throughout the surface.
• And there are a number of devices, such as hydraulic lifts and hydraulic brakes, that are based on Pascal’s law, these devices used fluids for transmitting pressure.

Concept:
According to Blaise Pascal, a French scientist observed that the pressure in a fluid at rest is the same at all points if they are at the same height and it is termed Pascal’s Law.

Proof of Pascal's law. ABC-DEF is an element of the interior of a fluid at rest. This element is in the form of a right-angled prism. The element is small so that the effect of gravity can be ignored, but it has been enlarged for the sake of clarity 
i.e., the pressure exerted by the fluid on an object at a certain height will be the same in all direction and hence it can be expressed as

From the above fig. we can see that the force against area within a fluid at rest will always experience pressure perpendicular to their surface area, and the object will experience equal pressure throughout the surface.
And there are a number of devices, such as hydraulic lift and hydraulic brakes, are based on Pascal’s law, these devices used fluids for transmitting pressure.

Pascal's Law:

• "Any force applied to a confined fluid is transmitted uniformly in all directions throughout the fluid regardless of the shape of the container".
  

The main applications of the hydraulic system are as follows:

• Industrial: Automated production lines, machine tool industries, Paper industries.
• Mobile hydraulics: Material handling equipment, commercial vehicles, tunnel boring equipment.
• Automobiles: It is used in the systems like hydraulic brakes, shock absorbers, steering system.
• Marine applications: It mostly covers ocean-going vessels, fishing boats, and naval equipment.

Concept:
Pascal’s Law:

• It was given by Blaise pascal
• It is also known as principle of transmission of fluid pressure
• It states that the pressure change at any point in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere.
• Alternate definition:- The pressure applied to any part of the enclosed liquid will be transmitted equally in all directions through the liquid.

Applications:

• The underlying principle of hydraulic jack and hydraulic press.
• Force amplification in the braking system of most motor vehicles.
• Used in artesian wells, water towers and dams.

Calculation:
Given:
Diameter of plunger, d = 1.5 cm, Diameter of ram, D = 15 cm, weight exerted on the ram, F₁ = 1000 kg
According to pascals law,
Pressure applied at plunger = Pressure exerted on the ram


Here, F₂ = force required on the plunger

Concept:
Pascal’s Law:

• It was given by Blaise pascal
• It is also known as the principle of transmission of fluid pressure
• It states that the pressure change at any point in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere.
• Alternate definition:- The pressure applied to any part of the enclosed liquid will be transmitted equally in all directions through the liquid.

Applications:

• The underlying principle of hydraulic jack and hydraulic press.
• Force amplification in the braking system of most motor vehicles.
• Used in artesian wells, water towers, and dams.

Calculation:
Given:
Diameter of plunger, d = 3 cm, Diameter of ram, D = 20 cm, Force required at the plunger = ?, Weight = 30 kN
According to pascals law,
Pressure applied at ram = Pressure exerted on the plunger

 

Here, F₂ = force required on the plunger

Pascal's law:
According to Pascal’s Law, the pressure or intensity of pressure at a point in a static fluid is equal in all directions.
This law is valid for the cases of fluid flow where shear stresses do not exist. The cases are

• Fluid at rest
• No relative motion exists between different fluid layers. For example, fluid at a constant linear acceleration in a container
• Ideal fluid flow where viscous force is negligible
  

Concept:

• Pascal’s principle: Pascal’s Law is the principle of transmission of fluid-pressure.
  • It says that "a pressure exerted anywhere in a point of the confined fluid is transmitted equally in all directions throughout the fluid”.
  • Hydraulic Lift: The lift that uses pascal's law and used to lift objects with the help of fluid is called hydraulic lift.  It works on Pascal's law. 
    

• The hydraulic ram is a pump that raises water without any external power for its operation.
• One essential requirement for the satisfactory operation of a hydraulic ram is the availability of a large quantity of water with a small positive head or height. This large quantity of water at a small height is sufficient to lift a small quantity of water to a greater height.
• The hydraulic system works on the principle of Pascal’s law which says that the pressure in an enclosed fluid is uniform in all directions.

The pressure intensity at a point in a fluid is the same in all directions, only when the fluid has no relative motion between adjacent fluid layers.

• Centrifuge: Centrifugation is used to separate the contents of mixtures according to their size and density. The centrifuge works on the principle of sedimentation.
• Hydraulic Lift: The lift that uses pascal's law and used to lift objects with the help of fluid is called hydraulic lift.  It works on Pascal's law. So option 2 is correct.
• ​Motor: A motor is an electrical device that converts electrical energy into mechanical energy. It works on the principle that a current-carrying conductor experiences a mechanical force when it is placed in a magnetic field.
• Lever: A lever is a simple machine that is made up of two load arms and a fulcrum. The distance from the fulcrum can be used to determine how the input and output forces are related to each other.