Definition
A set of physical principles describing the behavior of a moving fluid, stating that as the velocity of a fluid (such as air) increases, its internal pressure decreases, and as its velocity decreases, its pressure increases — provided the total energy of the flow remains constant.
Plain English
When air speeds up, it pushes outward less; when it slows down, it pushes outward more. Faster moving air has lower pressure than slower moving air around it.
Context Anchor
Seen in discussions of wing lift, airflow through narrowed passages, and aircraft systems that use moving air to create a pressure change.
Derivation
Named after Daniel Bernoulli, an 18th-century Swiss mathematician who described the relationship between the speed of a fluid and its pressure. Knowing the principle is named for a person — not a technical Latin or Greek root — helps the student treat it as a discovered law rather than a piece of jargon to decode.
Why Pilots Care
It explains why a wing creates lift when air moves faster over the top surface than the bottom.
Analogy
Think of squeezing a garden hose. Where you pinch it, the water speeds up — and the hose wall feels less outward push at that point. Faster flow, lower sideways pressure.
Grounding Statement
Picture air speeding up over part of a wing; in that faster-moving region, the air pressure is lower than in nearby slower-moving air.
Intuition Check
Bernoulli’s principles do not mean that faster air explains all lift by itself. They describe one pressure-speed relationship; the wing’s angle and the direction of the airflow also matter.
Example Sentence 1
The technician explained that the curved upper surface of the wing speeds the air across the top, and by Bernoulli's principles that faster air has lower pressure, contributing to lift.
Example Sentence 2
During the ground lesson the student saw how the wing shape applies Bernoulli’s principles to keep the airplane flying.