January 25, 2010
The motion of an airplane or helicopter through the air can be explained and distinguished by physical principals discovered over three centuries ago by Sir Isaac Newton, who worked in many areas of mathematics and physics. Throughout recent science history, three of the most important theories proven were all evaluated by Isaac Newton. He developed the theories of gravitation in 1666, when he was only 23 years old. Some twenty years later, in 1686, he presented his three laws of motion in the "Principia Mathematica Philosophiae Naturalis." Those discoveries are what we call today the Laws of Motion. Newton, who was born the same year that Galileo Galilei died, basically built on Galileo's ideas to demonstrate that the laws of motion in the heavens and the laws of motion on the earth were one and the same. He basically replaced the Aristotelian ideas that dominated the thinking of the best minds for most of the previous 2000 years. His first law states that every object continues in a state of rest, or of uniform speed in a straight line, unless acted on by a nonzero net force. This is normally taken as the definition of inertia. The key point here is that if there is no net force resulting from unbalanced forces acting on an object, if all the external forces cancel each other out, then the object will maintain a constant velocity. If that velocity is zero, then the object remains at rest. And if an additional external force is applied, the velocity will change because of the force. There are many applications of Newton's first law of motion. Consider some of your experiences in an automobile. Have you ever observed the behavior of coffee in a coffee cup filled to the rim while starting a car from rest or while bringing a car to rest from a state of motion? Coffee tends to "keep on doing what it is doing." When you accelerate a car from rest, the road provides an unbalanced force on the spinning...