Netwon's Laws Of Motion
Check us out at http://www.tutorvista.com Newton's laws of motion are three physical laws that form the basis for classical mechanics. They have been expressed in several different ways over nearly three centuries, and can be summarised as follows: 1.In the absence of a net force, the center of mass of a body either is at rest or moves at a constant velocity. 2.A body experiencing a force F experiences an acceleration a related to F by F = ma, where m is the mass of the body. Alternatively, force is equal to the time derivative of momentum. 3.Whenever a first body exerts a force F on a second body, the second body exerts a force ?F on the first body. F and ?F are equal in magnitude and opposite in direction. These laws describe the relationship between the forces acting on a body and the motion of that body. They were first compiled by Sir Isaac Newton in his work Philosophi? Naturalis Principia Mathematica, first published on July 5, 1687. Newton used them to explain and investigate the motion of many physical objects and systems.For example, in the third volume of the text, Newton showed that these laws of motion, combined with his law of universal gravitation, explained Kepler's laws of planetary motion. Newton's laws of motion are often defined as: •First Law: An object at rest tends to stay at rest, or if it is in motion tends to stay in motion with the same speed and in the same direction unless acted upon by a sum of physical forces. •Second Law: A body will accelerate with acceleration proportional to the force and inversely proportional to the mass. •Third Law: Every action has a reaction equal in magnitude and opposite in direction.