# What is Bernoulli’s theorem and its application on ship?

Definition: In fluid dynamics, Bernoulliâ€™s theorem states that the total energy of moving fluid consisting of the gravitational potential energy of the elevation, the energy associated with the fluid pressure and the kinetic energy of the moving fluid is constant. In simple terms, it is the relation between pressure, velocity and elevation of moving fluid.

Conservation of energy states that energy can neither be created nor be destroyed, it can only be converted from one form to another form of energy.

## What are the applications of Bernoulliâ€™s equation?

### 1. Venturimeter

A venturi meter measures the flow of fluid in a pipe that has a non-uniform cross-section..  Venturimeter works on the principle of Bernoulliâ€™s theorem. When fluid passes through the inlet and gets to the constricted section of the pipe, it creates a pressure difference in both sections due to the increase in velocity of the fluid. Two pressure gauges are connected in both sections and the flow rate can be calculated by taking the difference between pressures at both sections.

### 2. Water sprayer

In a water sprayer when piston is pulled as the volume is increasing a vacuum is being created decreasing the pressure , which is less than the pressure , due to which water sucks in from the vertical tube attached to the container.

Then the piston is pressed the air and water mixture rushes out of the horizontal tube. Water breaks up into fine spray along with the air and flows out of the nozzle.

### 3. Lifting of an aircraft

An aircraft lifts in air because of the wing called an airfoil. The wing is designed in such a way that the air passing above the wing of the aircraft and below the wing has different velocities but they reaches at the end point at the same time. The wing upper surface is curved so the air above the wing speeds up and stretches out which decreases the air pressure above the wing.

On the other side the air flowing below the wing flows in a straighter line thus its speed and pressure doesnâ€™t changes which is high pressure. Since high pressure always moves to low pressure (According to Bernoulliâ€™s theorem) the air below the wing pushes upward toward the air above the wing and the aircraft tends to keep flying.

## Application of Bernoulli’s theorem on a ship:

1. In Pumps: When liquid passes through volute casing, the area of the volute casing is gradually increasing due to which some of the kinetic energy is getting converted into pressure energy.

### Note:

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