Newton's laws of motion

Three principles describing inertia, how net force changes momentum, and the equal-and-opposite forces in interactions. They form the basis of classical mechanics for motion viewed in inertial frames.

Newton's first law: An object remains at rest or moves at constant velocity unless acted on by a net external force. It defines inertial motion and identifies when a force changes it.
Force: An interaction that can change a body's momentum. Net force is the central quantity relating interactions to motion.
Aristotelian physics: An ancient natural philosophy in which continued motion generally requires a continuing mover. Newton's first law rejects the idea that motion needs continuous maintenance.
Projectile motion: The motion of an object moving through the air under gravity, often modeled without air resistance. Its curved path follows from combining horizontal inertia with vertical gravitational acceleration.
Isaac Newton: An English mathematician and natural philosopher who formulated classical mechanics and the law of universal gravitation. He stated the three laws in his 1687 work, the Principia.
Newton's second law: The net force on a body equals the time rate of change of its momentum; for constant mass, it is mass times acceleration. It quantifies how net force changes an object's motion.
Mass: A physical property measuring inertia and, in classical mechanics, the proportionality between force and acceleration. Mass measures how strongly a body resists acceleration under a given net force.
Special relativity: Einstein's theory of space, time, and motion for inertial frames, especially at high speeds. Newtonian laws cease to be accurate when speeds approach the speed of light.
Friction: A force that resists relative motion or attempted motion between surfaces in contact. Friction contributes to the net force that determines acceleration.
Philosophiæ Naturalis Principia Mathematica: Isaac Newton's 1687 book presenting laws of motion and universal gravitation. It introduced the laws as part of a mathematical account of physical motion.

Linked from 89 pages