Editing Motion (section)

=== Classical mechanics ===
{{Main|Kinematics}}
Classical mechanics is used for describing the motion of [[macroscopic]] objects moving at speeds significantly slower than the speed of light, from [[projectiles]] to parts of [[machinery]], as well as [[astronomical objects]], such as [[spacecraft]], [[planets]], [[star]]s, and [[Galaxy|galaxies]]. It produces very accurate results within these domains and is one of the oldest and largest scientific descriptions in [[science]], [[engineering]], and [[technology]].

Classical mechanics is fundamentally based on [[Newton's laws of motion]]. These laws describe the relationship between the forces acting on a body and the motion of that body. They were first compiled by [[Isaac Newton|Sir Isaac Newton]] in his work ''[[Philosophiæ Naturalis Principia Mathematica]]'', which was first published on July 5, 1687. Newton's three laws are:
# A [[Physical body|body]] at rest will remain at rest, and a body in motion will remain in motion unless it is acted upon by an external force. (This is known as the law of [[inertia]].)
# Force (<math>\vec{F}</math>) is equal to the change in momentum per change in time (<math> \frac{\Delta m\vec{v}}{\Delta t}</math>). For a constant mass, force equals mass times acceleration (<math>\vec{F} = m\vec{a} </math> ).
# For every action, there is an equal and opposite reaction. (In other words, whenever one body exerts a force <math>\vec{F}</math> onto a second body, (in some cases, which is standing still) the second body exerts the force <math>-\vec{F}</math> back onto the first body. <math>\vec{F}</math> and <math>-\vec{F}</math> are equal in magnitude and opposite in direction. So, the body that exerts <math>\vec{F}</math> will be pushed backward.)<ref>Newton's "Axioms or Laws of Motion" can be found in the "[[Mathematical Principles of Natural Philosophy|Principia]]" on [https://books.google.com/books?id=Tm0FAAAAQAAJ&pg=PA19 p. 19 of volume 1 of the 1729 translation] {{Webarchive|url=https://web.archive.org/web/20150928021402/https://books.google.com/books?id=Tm0FAAAAQAAJ&pg=PA19 |date=2015-09-28 }}.</ref>

Newton's three laws of motion were the first to accurately provide a mathematical model for understanding [[orbit]]ing bodies in [[outer space]]. This explanation unified the motion of celestial bodies and the motion of objects on Earth.