Motion (physics) Isaac Newton in his work "Philosophiæ Naturalis Principia Mathematica", first published on July 5, 1687. Newton's three laws are: Newton's three laws of motion were the first to accurately provide a mathematical model for understanding orbiting bodies in outer space. This explanation unified the motion of celestial bodies and motion of objects on earth. Classical mechanics was further enhanced by Albert Einstein's special relativity and general relativity. Special relativity is concerned with the motion of objects with a high velocity, approaching the speed of light; general relativity is employed to handle gravitational motion at a deeper level. Uniform Motion: When
Gravity current intrusion Gravity current intrusion The term gravity current intrusion denotes the fluid mechanics phenomenon within which a fluid intrudes with a predominantly horizontal motion into a separate stratified fluid, typically along a plane of neutral buoyancy. This behaviour distinguishes the difference between gravity current intrusions and gravity currents, as intrusions are not restrained by a well-defined boundary surface. As with gravity currents, intrusion flow is driven within a gravity field by density differences typically small enough to allow for the Boussinesq approximation. The driving density difference between fluids that produces intrusion motion could simply be due to chemical composition. However variations