Newton's First Law

<h1>Text Preview</h1> <p> The relationship between force and motion is called dynamics... and is the basis of Newton's laws of motion. The study of dynamics deals with such questions as: Why do things move the way they do? What causes an object at rest to start moving? And, what causes a moving object to stop? Let's get started... Force is defined as any kind of a push or a pull on an object. Pushing a crate requires force, as does throwing a ball. In 1687, Sir Isaac Newton, an English physicist and mathematician, published The Principia, in which he detailed Newton's Laws of Motion. Let's examine these laws one by one. Newton's First law states that "Every body continues in its state of rest or of uniform speed in a straight line unless acted on by a nonzero net force." This means that, unless forces act on this crate, it will remain stationary. In order to move the crate, we must exert a force on it. Similarly, an object in motion will remain in motion unless... acted on by a force. In other words, no force means no change in velocity. The natural tendency ot objects to resist changes in their state of motion is called inertia. The mass of an object is a measure of its inertia. The greater the mass of an object, the greater the force needed to move it. The SI unit of mass is the kilogram. Don't confuse mass and weight. Mass is a property of an object, whereas weight is actually a force. In the real world, objects often slow down and stop without any apparent forces acting on them. Why do you think this happens? ... To make things simpler, we will be ignoring friction for the moment. ... You have completed Newton's First Law lecture.</p> <p id="TextCopyright">Copyright 2006 The Regents of the University of California and Monterey Institute for Technology and Education</p>