3 Laws of Motion

Christian Hernandez
January 25, 2010
Physics
Mr. Savage

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 wheels to push the car forward; yet the coffee (which was at rest) wants to stay at rest. While the car accelerates forward, the coffee remains in the same position; subsequently, the car accelerates out from under the coffee and the coffee spills in your lap. On the other hand, when breaking from a state of motion the coffee continues forward with the same speed and in the same direction, ultimately hitting the windshield or the dash. Coffee in motion tends to stay in motion.
Newton’s second law of motion states that the acceleration produced by a net force on an object is directly proportional to the magnitude of the net force and is inversely proportional to the mass of an object. In a brief form basically, Acceleration equals net force divided by mass. Acceleration can also equal change in velocity divided by the time interval. Therefore force equals mass multiplied by acceleration. A perfect everyday life example of Newton’s second law of motion is let’s having said your friend is on a skateboard. You push him forward, and he moves a decent amount of distance. A little push and your friend and the skateboard begin to move slowly. A big push, and he moves faster, and gains speed more quickly. Then your friend gets in his automobile. You push the automobile and it is very difficult to move. You push harder, and it barely begins to move. All your friends together push the car and the automobile begins to moves faster and faster. This example shows the way acceleration is proportioned. The heavier the mass, the harder it is too begin the acceleration; but a light mass will accelerate in no time.
Everyone has heard the saying, “when you jump off a building, it is not the fall that kills you but the sudden stop.” That’s an unfortunate example of Isaac Newton’s third and final law of motion which states that whenever one object exerts a force on a second object, the second object exerts an equal and opposite fore on the first object. There are many everyday examples of how we use this law in everyday life and probably do not even know it. For example, when you accelerate a car, what is really making it move if the tires are pushing the road and the road pushing the tires forward making the car accelerate in the direction you wish. According to Newton’s Second Law of Motion we must always consider the amount of the mass of an object. For example, when you light the fuse to a cannon, the cannonball launches really far while the cannon only recoils a little bit. Why is that you might ask. Simply because the cannon has more mass than the cannonball. They are both being exerted with the same amount of force but since the cannonball is way lighter in mass, that explains why it goes much further than the cannons recoil.
All in all, the discoveries of Sir Isaac Newton still up to this day have a magnificent impact on our lives whether we know it or not. Through his discoveries is why we as mankind have been able to fly to the moon, search very far underneath water level or even been able to fly to different countries. The impacts of his laws are unbelievably important to the future in technology and basically everything else in the world. Although he based his theories on pass laws he did give credit where it was due through a famous quote by Newton himself, “if I have seen further it is by standing on the shoulders of giants.”