The liquid fluid laws are fundamental principles that describe the behavior of liquids in motion or at rest. These laws, such as the continuity equation, Bernoulli's Law, Pascal's Law and Archimedes' Law, among others, are crucial in various disciplines such as engineering, physics and biology.

They provide a theoretical framework for understanding fluid mechanics phenomena such as the flow of liquids in piping systems, the flotation of objects in fluids, aircraft design, and blood circulation in the human body.

Below we offer a simplified explanation of these laws, principles and equations.

## Continuity equation

Let's imagine a mighty river that flows constantly. The continuity equation tells us that the amount of water entering a given point in the river must be equal to the amount leaving at the same point, as long as there is no accumulation or loss of water in the system.

This law establishes a direct relationship between the velocity and the cross-sectional area of a fluid flow. In engineering, this law is often applied in the design of pipe and channel systems to ensure uniform and efficient flow of liquids.

## Bernoulli's Law

If you've ever blown on the surface of a hot drink to cool it, you've experienced Bernoulli's law in action. This law establishes a relationship between the pressure, velocity and height of an incompressible fluid in motion.

In frictionless flow, the total energy of the fluid (kinetic, potential, and pressure) remains constant throughout the flow. Planes fly, roller coaster cars slide, and raindrops fall because of the principles described by this law.

## Pascal's Principle

Imagine a water bag with several straws inserted. If you apply pressure to one straw, all the others will feel the effect. Pascal's principle states that the pressure applied at one point of a fluid contained in a container is transmitted without decrease to all points of the fluid and to the walls of the container.

This principle of fluid engineering is applied in hydraulic engineering and in understanding the operation of devices such as hydraulic jacks used to lift cars in mechanical workshops.

## Archimedes' principle

When you dive into a pool, you experience Archimedes' principle in action. This principle states that an object immersed in a fluid experiences a buoyant force equal to the weight of the volume of fluid displaced by the object.

For example, ships float because the water they displace weighs as much as the ship itself. Using this law, phenomena such as the floating of icebergs and the formation of ocean currents can be studied.

## Stokes's Law

This law, developed by British physicist George Gabriel Stokes in the 19th century, describes the drag force experienced by a small-sized spherical particle moving through a viscous fluid at relatively low speeds.

Stokes' law is especially relevant in micro fluid dynamics and in applications where the movement of small particles in viscous liquids plays an important role, such as in the sedimentation of suspended particles, the diffusion of particles in biological fluids, and filtration in filtration systems. membranes. In addition, it is used in the determination of fluid viscosities through experimental techniques such as viscometry.

An example of this law occurs when a raindrop slowly falls through the window, you are seeing Stokes' law in action.