Which scientist proposed the three laws of motion in Principia Mathematica?

Isaac Newton proposed the three laws of motion in Principia Mathematica.

Newton presented the laws in his 1687 work Philosophiæ Naturalis Principia Mathematica, usually shortened to Principia. The book also developed his mathematical treatment of gravity and motion, helping establish classical mechanics as a unified science.

The first law describes inertia: an object maintains its state of motion unless acted on by a net external force. The second connects force, mass, and acceleration, commonly written as F = ma. The third states that interacting bodies exert equal and opposite forces on each other.

Newton built on earlier work by Galileo Galilei and Johannes Kepler. His laws work extremely well for ordinary speeds and sizes, although relativity and quantum mechanics are needed for extreme conditions. The laws remain central to engineering, astronomy, and everyday mechanics.