Sir Isaac Newton in his 1687 Philosophiae Naturalis Principia Mathematica published observations that would form the foundation of classical mechanics. Perhaps most famously, Newton,s book lays out the law of universal gravitation. But just as important, the Principia puts forth Newton,s three laws of motion and energy.
The first law says that an object will retain its state of motion unless some external force acts on it. If it’s moving, it will keep moving; if at rest, it will remain so.
The second law describes how much force is required to achieve a given change in the velocity of a particular mass (Force=Mass X Acceleration). Put another way, it predicts the acceleration of a mass when a given fore is applied. Newton’s third law asserts that for every action, there is a reaction, there is a reaction of equal magnitude in the opposite direction.
” If i have seen further ” Newton wrote, ” it is by standing on the shoulder of giants.’ Newton did draw deeply on the work of earlier philosophers, physicists, and mathematicians. But it was he who showed that the physical world is governed by universal, mathematical laws – and who began to set down those laws in elegant formulations borne out by centuries of observation. Newton’s laws advanced the scientific revolution of the seventeenth century and laid a foundation for the industrial revolution of the nineteenth century.
These laws describe the behavior of idealized particles or points. Objects can often be treated as points when studying motion, but their movement involves more complex dynamics. A half – century after Newton, Swiss physicist Leonhard Euler extended Newton’s work in two laws that describe the movement of bodies made up of an assemblage of points.
RESISTANT TO CHANGE – NEWTON;S FIRST LAW OF MOTION
Absent some force acting on it, a ball sitting on the floor will just sit there. A ball rolling along a perfectly fric tionless and even surface will likewise continue rolling, in the same direction and at the same speed, indefinitely.
Indeed, according to Newton’s first law of motion – more familiarly known as the law of inertia – all objects inherently resist change in their state of motion. A thing at rest remains at rest, and an object in motion keeps moving in the same direction and at the same speed, unless some outside force disrupts it.
SEGWAY – Newton’s First Law of Motion
Unveiled in 2001, the Segway PT ( Personal Transporter ) is a two wheeled, self – balancing, electric powered vehicle designed to mimic the naturalness of walking and turning – and maybe even pausing to smell the roses. Its movement responds to subtle shifts in the user’s body weight forward, backward, and to the side while remaining upright. Riders steer by learning in the direction they want to go. This balancing act involves a high – tech elaboration o Newton’s law of inertia. It’s based on five miniature silicon gyroscopic devices coupled with electronic sensors that monitor change in the pitch of the vehicle’s platform in comparison with the inertial movement of the gyroscopes.
Just about everyone is familiar with one gyroscopic instruments – the child’s spinning top, developed independently in ancient civilizations around the world. Why does it go on spinning? Inerita. A moving object will persist in its motion, along the same axis, unless a force acts to change or stop it.
In 1952 French physicist Leon Foucault created a precision gyroscope and gave the instrument its name, made up of Greek words meaning essentially rotation watcher. While holding his gyroscope ca
ge steady, Foucault showed that the angle of the inner disk’s rotation seemed to change very gradually on its own. In fact it was the frame moving ; this was an early demonstration of Earth’s own rotation on its axis.
Once in motion, the gyroscope’s inner wheel maintains the orientation of its rotation even as its outer frame is tilted. Because of this, the gyroscope is a tremendously useful tool in setting or maintaining direction in a number of applications, from aircraft navigation to missile guidance to tunnel mining.
Hold the hub of a swiftly spinning bicycle wheel, and try to change its angle of rotation; you’ll feel it resist. Its tendency to maintain orientation makes the wheel seem to push back in the other direction.
Angular momentum refers to the tendency of rotating objects to continue rotating unless acted on by a torque. This natural persistence of angular momentum is the basis for gyro-stabilizers in ships. As a craft encounters the kind of wave that makes ocean travel hopelessly nauseating for some, the spinning rotor of the stabilizer resists, exerting a counter force that keeps the vehicle from rolling.
The first gyroscopic ship stabilizers were used in United States naval ships and large ocean liners in the early twentieth century. They relied on the mass of the main stabilizing gyro itself to right the vessel. The Navy’s first gyro – stabilizer was placed in the hold of a small destroyer and weighed five tons. Later, designers adapted this method by using smaller gyroscopes whose rotational force controls stabilizing fins that extended from the ship’s hull.
Aim a gyroscope’s axis at true north, and it will continue to aim there, no matter what orientation is take by its outer frame. This is the basis for gyrostabilizers used to keep a plane flying level. Inventor Lawrence B. Sperry, who developed the first such stabilizers for ships, first wowed the public with his three – way flight gyrostabilizer at the International Airplane Safety Competition in Paris in 1914. This gyroscope’s inertial rotation controlled movement along the plane’s three axes of movement – yaw (nose right or left), pitch (nose up or down), and wing – to – wing roll. Sperry thrust his arms in the air, releasing the controls; the gyroscope worked like an automatic pilot.
Similar technology helps point the Hubble Space Telescope, launched in 1990. A wheel inside each of six gyroscopes spins at a rate of 19,200 revolutions per minute on gas bearings. Electronic sensors in the gyros relay information about even slight movements of the scope to Hubble’s central computer.
This everyday household appliance ingeniously applies Newton’s insights to the wringing of soaked laundry, a chore roundly dreaded in the pre – industrial age as the most strenuous part of washday. According to Newton’s first law of motion, matter will move in a straight line unless forced to do otherwise. In the washing machine’s spin cycle, the drum rotates rapidly, its inner walls continually pushing the clothes into a circular path. This directional change by definition means the clothes are accelerating and thus subject to external force. The rapid mechanical spinning can exert quite substantial force, as anyone who has witnessed the banging of an unevenly loaded washer can attest.
But holes in the walls of the drum mean no such inward force acts on the water. The wash water is permitted to fly off along the linear path predicted by Newton, effectively wringing the clothes against the spinning drum.