What is the Bernoulli's principle in relation to fluid pressure?

Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in its pressure.

Bernoulli's principle is a fundamental concept in fluid dynamics, which is a branch of physics that studies the behaviour of fluids in motion. Named after the Swiss scientist Daniel Bernoulli, this principle explains the relationship between the speed of a fluid and its pressure.

Imagine a fluid flowing through a pipe. If the pipe narrows, the fluid has to speed up to get through. According to Bernoulli's principle, as the speed of the fluid increases, its pressure decreases. Conversely, if the pipe widens, the fluid slows down, and its pressure increases. This principle is applicable to both liquids and gases, as they are both considered fluids.

This principle is based on the law of conservation of energy. The total energy in a steadily flowing fluid system is constant along the flow path. The energy of a fluid particle is made up of its kinetic energy (due to its velocity), potential energy (due to its height), and pressure energy. If the kinetic energy increases (i.e., the fluid speeds up), the pressure energy must decrease to keep the total energy constant, and vice versa.

Bernoulli's principle has many practical applications. For example, it explains why an aeroplane can lift off the ground. The shape of an aeroplane's wing (known as an airfoil) is designed so that air flows faster over the top of the wing than underneath. According to Bernoulli's principle, this means the pressure is lower on top of the wing than underneath, creating an upward force called lift.

In summary, Bernoulli's principle is a fundamental concept in fluid dynamics that describes the inverse relationship between the speed and pressure of a fluid.