Newton's laws of motion

Newton's laws of motion are three physical laws that describe the relationship between the motion of an object and the forces acting on it. These laws, which provide the basis for Newtonian mechanics, can be paraphrased as follows:

1. A body remains at rest, or in motion at a constant speed in a straight line, unless it is acted upon by a force.
2. At any instant of time, the net force on a body is equal to the body's acceleration multiplied by its mass or, equivalently, the rate at which the body's momentum is changing with time.
3. If two bodies exert forces on each other, these forces have the same magnitude but opposite directions.

• Newton’s glory was to fulfil, in his Principia of 1687, Galileo's hope of geometrizing gravitation. The ingredients of his solution were Descartes' first law of motion (the principle of inertia), Galileo's rules of free fall and composition of velocities, and Kepler's rules of planetary orbiting. Newton showed that Kepler's rules following form Galileo's, the principle of inertia, and the assumption that a planet falls towards the Sun along the line joining their centres. Since Kepler's rules allowed the substitution of an area for a time, Newton could reduce the problem of the magnitude of gravitational acceleration to a problem in geometry.
  • John L. Heilbron, The History of Physics: A Very Short Introduction. Volume 549 of Very Short Introductions (pbk ed.). Oxford University Press. 2018. p. 79. ISBN 9780199684120.  (175 pages; first published in 2015 under the title Physics: A Short History from Quintessence to Quarks)

• Lex I. Corpus omne perseverare in statu suo quiescendi vel movendi uniformiter in directum, nisi quatenus a viribus impressi cogitur statum illum mutare.
  Lex II. Mutationem motus proportionalem esse vi motrici impressa; & fieri secundum lineam rectam qua vis illa imprimatur.
  Lex III. Actioni contrariam semper & aequalem esse reactionem: sive corporum duorum actiones in se mutuo semper esse aequales & in partes contrarias dirigi.
  (English translation: Law I. Every body perseveres in its state of rest or of uniform motion in a straight line, except in so far as it is compelled to change that state by the forces impressed upon it.
  Law II. The change of motion is proportional to the motive force impressed upon it; and takes place along the straight line on which that force is impressed.
  Law III. To an action there is always an opposite and equal reaction: or the actions of two bodies on each other are always equal and directed in opposite directions.)
  • Newton, Isaac (2023). "Axiomata Sive Leges Motus". Philosophiae Naturalis Principia Mathematica (Latin): Philosophiae Naturalis Principia Mathematica: Sir Isaac Newton's Groundbreaking Laws of Physics (unabridged ed.). Prabhat Prakashan.  (970 pages)

• Classical mechanics
• Scientific revolution

• Encyclopedic article on Newton's laws of motion on Wikipedia