Applications of pascal’s law

Applications:Pascal’s law for transmission of fluid pressure

Hydraulic lift:-

  • Hydraulic lift is a lift which makes use of a fluid.
    • For example: Hydraulic lifts that are used in car service stations to lift the cars.
  • Principle: –
  • Inside a hydraulic lift there are 2 platforms,one has a smaller area and the other one has a larger area.
  • It is a tube like structure which is filled with uniform fluid.
  • There are 2 pistons (P1 and P2)which are attached at both the ends of the tube.
  • Cross-sectional area of piston P1 is A1 and of piston P2 is A2.
  • If we apply force F1 on P1, pressure gets exerted and according to Pascal’s law the pressure gets transmitted in all the directions and same pressure gets exerted on the other end.As a result the Piston P2 moves upwards.
  • Advantage of using hydraulic lift is that by applying small force on the small area we are able to generate a larger force.
  • Mathematically:- F2=PA2
    • where F2 = Resultant Force,A2 = area of cross-section
    • F2= (F1/A1)A2 where P=F1/A1 (Pressure P is due to force Fon the area A1)
    • F2 =(A2/A1)F1. This shows that the applied force has increased by A2/A1.
  • Because of Pascal’s law the input gets magnified.

Applications of pascal's law

Applications of pascal's law

The above figure shows the internal structure of the hydraulic lift.

Hydraulic Brakes

  • Hydraulic brakes work on the principle of Pascal’s law.
  • According to this law whenever pressure is applied on a fluid it travels uniformly in all the directions.
  • Therefore when we apply force on a small piston, pressure gets created which is transmitted through the fluid to a larger piston. As a result of this larger force,uniformbrakingis applied on all four wheels.
  • As braking force is generateddue to hydraulic pressure,theyare known as hydraulic brakes.
  • Liquids are used instead of gas as liquids are incompressible.

Construction

  • The fluid in the hydraulic brake is known as brake fluid.
  • It consists of a master cylinder, four wheel cylinders and pipes carrying brake fluid from master cylinder to wheel cylinders.
  • Master cylinder consists of a piston which is connected to pedal through connecting rod. 
  • The wheel cylinders consist of two pistons between which fluid is filled.
  • Each wheel brake consists of a cylinder brake drum. This drum is mounted on the inner side of wheel. The drum revolves with the wheel.
  • Two brake shoes whichare mounted inside the drum remain stationary.

Working

  • When we press the brake pedal, piston in the master cylinder forces the brake fluid through a linkage.
  • As a result pressure increases and gets transmitted to all the pipes and to all the wheel cylinders according to Pascal’s law.
  • Because of this pressure,both the pistons move outand transmit the braking force on all the wheels.

Advantages:-

  • Equal braking effort to all the four wheels.
  • Less rate of wear due to absence of joints.
  • By just changing the size of one piston and cylinder, force can be increased or decreased.

Disadvantages:-

  • Leakage of brake fluid spoils the brake shoes.
  • Even the slightest presence of air pockets can spoil the whole system.

Applications of pascal's law

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