Newton's laws of motion are three physical laws that form the basis for classical mechanics. They describe the relationship between the forces acting on a body and its motiondue to those forces. They have been expressed in several different ways over nearly three centuries, and can be summarized as follows:
1. First law: The velocity of a body remains constantunless the body is acted upon by an external force.
2. Second law: The acceleration a of a body is parallel and directly proportional to the net force F and inversely proportional to themass m, i.e., F = ma.
3. Third law: The mutual forces of action and reaction between two bodies are equal, opposite and collinear.
The three laws of motion were first compiled by Sir Isaac Newton inhis work Philosophiæ Naturalis Principia Mathematica, first published in 1687. Newton used them to explain and investigate the motion of many physical objects and systems. For example, in thethird volume of the text, Newton showed that these laws of motion, combined with his law of universal gravitation, explained Kepler's laws of planetary motion.
This article isabout Bernoulli's principle and Bernoulli's equation in fluid dynamics. For Bernoulli's Theorem (probability), see Law of large numbers. For an unrelated topic in ordinary differential equations, seeBernoulli differential equation.
A flow of air into a venturi meter. The kinetic energy increases at the expense of the fluid pressure, as shown by the difference in height of the two columns ofwater.
In fluid dynamics, Bernoulli's principle states that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid'spotential energy. Bernoulli's principle is named after the Dutch-Swiss mathematician Daniel Bernoulli who published his principle in his book Hydrodynamica in 1738.
Bernoulli's principle can...