Sir Isaac Newton is a great Scientist in the History. He found The Universal Law of Gravitation. Sir Isaac Newton is a great Scientist for all time. Sir Isaac Newton Kt, PRS (/ njuːtən / December 25, 1642 - March 20, 1726-1727) was an English physicist and mathematician (described at the time as a "natural philosopher"), which is widely recognized as one of the scientists most influential of all time and a key figure in the scientific revolution. His book Philosophiae Naturalis Principia Mathematica ( "Mathematical Principles of Natural Philosophy"), first published in 1687, laid the foundations of classical mechanics. Newton made seminal contributions to optics, and shares credit with Gottfried Leibniz for the development of calculus.
Principia of Newton formulated the laws of motion and universal gravitation, which dominated view of the physical universe of scientists for the next three centuries. By deriving the laws of planetary motion Kepler his mathematical description of gravity, then using the same principles to account for the paths of comets, the tides, the precession of the equinoxes, and other phenomena, Newton eliminated the last doubts about the validity of the heliocentric model of the solar system. This work also showed that the motion of objects on Earth and of celestial bodies could be described by the same principles. His prediction that the Earth must be in the form of an oblate spheroid was later claimed by measurements of Maupertuis, La Condamine, and others who helped convince most continental European scientists of the superiority of the mechanics of Newton the previous system of Descartes.
Newton built the first practical reflecting telescope and developed a theory of color based on the observation that a prism decomposes white light into the various colors of the visible spectrum. He formulated an empirical law of cooling, studied the speed of sound, and introduced the notion of a Newtonian fluid. Besides his work in the calculation, as a mathematician Newton contributed to the study of power series, I generalized binomial theorem for non-integer exponent, developed a method for approximating the roots of a function, and most cubic plane curves is classified.
Newton was a fellow of Trinity College and the second Lucasian professor at Cambridge University. He was a devout Christian, but unorthodox and unusual for a member of the faculty of Cambridge the day way, refused to take holy orders in the Church of England, perhaps because rejected privately doctrine of the Trinity . Beyond his work in mathematical science, Newton spent much of his time to the study of biblical chronology and alchemy, but most of their work in these areas remained unpublished until long after his death. In his later life, Newton became president of the Royal Society. Newton served the British government as Guardian and Master of the Royal Mint.
Universal Law of Gravitation
There is a popular story that Newton was sitting under an apple tree, an apple fell on his head, and suddenly thought of the universal law of gravitation. As this is in all these legends, almost certainly not in detail, but the story contains elements of what actually happened.
What Really Happened with the Apple?
Probably the most correct version of the story is that Newton, observing an apple fall from a tree, began to think about the following terms: the apple is accelerated, as their speed changes from scratch, as it is hanging on the tree and moves toward the ground. Therefore, by Newton's second law has to be a force acting on the block to make this acceleration. Let's call this force "gravity", and acceleration associated with the "acceleration of gravity". Then you imagine the apple is twice as high. Again, we expect the apple to accelerate toward the ground, so this suggests that this force we call gravity reaches the top of the apple tree top.
Sir Isaac's Most Excellent Idea
Now it's really bright vision of Newton: if the force of gravity reaches the top of the tallest tree, I could not go further; in particular, it could not reach all the way to the orbit of the Moon! Then, the orbit of the Moon around the Earth could be a consequence of the force of gravity, because the acceleration of gravity could change the speed of the Moon in just such a way that followed an orbit around the earth.
This can be illustrated by the experiment shown in the following figure. Suppose you shoot a cannon horizontally from a high mountain; the projectile will ultimately fall to the ground, as indicated by the shortest path in the figure, due to the gravitational force directed toward the center of the Earth and the associated acceleration. (Remember that acceleration is a change of speed and velocity is a vector, so it has a magnitude and a direction. Thus, an acceleration occurs if one or both the magnitude and direction of change of speed).
But as output increases the speed of our imaginary guns, the projectile will travel more and more before returning to earth. Finally, Newton reasoned that if the barrel projects the cannonball with exactly the right speed, the projectile would travel completely around the earth, always falls in the gravitational field, but never reaches the Earth, curving away to the same speed the projectile falls. That is, the cannonball would have been placed in orbit around the Earth. Newton concluded that the orbit of the Moon was exactly the same nature: continuous Moon "fell" in its path around the Earth due to the acceleration of gravity, producing its orbit.
By such reasoning, Newton concluded that any two objects in the universe exert gravitational attraction on the other, with the force that has a universal form:
The constant of proportionality G is known as the gravitational constant. It is called a "universal constant" as it is thought to be the same in all places and all times, and therefore universally characterized the intrinsic strength of the gravitational force.
The Center of Mass for a Binary System
If you think about it for a moment, it may seem a little strange that Kepler's laws del Sol is set at a point in space and the planet revolves around it. Why the Sun is privileged? Kepler had more mystical ideas about the Sun, ending with godlike qualities that justified their special place. However Newton, largely as a corollary of his third law showed that the factual situation was more symmetrical than Kepler imagined and that the sun does not occupy a privileged position; in the process Kepler's 3rd Law is changed.
Consider the diagram shown on the right. We can define a point called the center of mass between two objects through the equations.
where R is the total separation between the centers of the two objects. The center of mass is familiar to anyone who has played on a seesaw. The fulcrum on which the seesaw balance exactly two people sitting at each end is the center of mass for the two people sitting on the seesaw.
Here is a center mass calculator that will help you make and visualize the calculations of the center of mass. (Caution: This applet is written in Java 1.1 language, which is only compatible with existing browsers should work on Windows systems with Netscape 4.06 or the latest version of Internet Explorer 4.0, but can not run on Mac or Unix systems or browsers. Windows above).
Newton's Modification of Kepler's Third Law
Because for every action there is an equal and opposite reaction, Newton realized that the planet-sun planet system is not in orbit around a stationary Sun Instead, Newton proposed that both the planet and the sun orbited around the common center of mass for the planet-Sun system. Then the third Kepler law is modified to read,
where P is the planetary orbital period and the other variables are as described above, with the Sun as a planet mass and the other mass. (As in the previous discussion of the Law 3rd Kepler, this form of the equation assumes that the masses are measured in solar masses, times years from Earth, and distances in astronomical units.) Note the symmetry this equation because the masses the left side are added and the distances are added on the right side, it does not matter if the sun is marked with 1 and 2 with the planet, or vice versa. the same result is obtained in both cases.
Now notice what happens in the new equation of Newton, if one of the masses (either 1 or 2; remember symmetry) is very large compared to the other. In particular, suppose that the sun is labeled mass 1 and its mass is much greater than the mass of any of the planets. Then the sum of the two masses is always approximately equal to the mass of the sun, and if we proportions of Law 3rd Kepler for two different planets to the masses cancel from the relationship and stayed with the original form of the 3rd law Kepler:
So Kepler's third law is approximately valid because the Sun is much more massive than any of the planets and therefore Newton correction is small. Kepler data accessed was not good enough to show this small effect. However, the detailed observations made after Kepler show that the modified form of Newton's third law of Kepler is in better agreement with the data than the original form of Kepler.
Two Limiting Cases
We can gain a greater understanding considering the position of the center of mass in two limits. Consider first the example just discussed, where a mass is much bigger than the other. So we see that the center of mass of the system essentially coincides with the center of mass object:
This is the situation in the solar system: the Sun is so large compared to any of the planets that the center of mass of a pair of Sun-planet is always very close to the center of the Sun Therefore, for all practical purposes the sun is almost (but not quite) motionless in the center of mass of the system, as Kepler originally thought.
But now consider another limiting case where the two masses are equal. Then it is easy to see that the center of gravity is equidistant from the two masses and if they are gravitationally bound together, each mass orbit around the common center of mass for the system lying halfway between them:
This situation commonly occurs with binary star (two stars gravitationally bound to each other so that revolve around their common center of mass). In many binary star systems the masses of the two stars are similar and correction of Newton 3rd Law Kepler is very large.
Here is a Java applet that implements a modified form of Newton's third law of Kepler for the two objects (planets or stars) that revolve around their common center of mass. By making a much larger mass than the other in this interactive animation you can illustrate the ideas discussed above and recover the original form of Kepler's third law, when a less massive object seems to revolve around a massive object set in one of the foci of an ellipse.
These limiting cases the location of the center of mass are perhaps familiar with our aforementioned playground experience. If people are of equal weight in a seesaw, the fulcrum should be placed in the middle for balance, but if a person weighs more than the other person, the fulcrum is placed near the heavier person to achieve balance.
Here is a calculator Kepler's laws which allows you to make simple calculations for periods, separations, and the masses of the Kepler laws' modified by Newton (see next section) to include the effect of the mass center. (Caution: This applet is written in Java 1.1 language, which is only compatible with existing browsers should work on Windows systems with Netscape 4.06 or the latest version of Internet Explorer 4.0, but can not run on Mac or Unix systems or browsers. Windows above).
Weight and the Gravitational Force
We have seen that in the Law of Universal Gravitation of the amount of mass is essential. In popular parlance mass and weight are often used to mean the same thing; actually are related but different things. What we commonly call weight is really only the gravitational force exerted on an object of a certain mass. We can illustrate by choosing Earth as one of the two masses in the above illustration of the law of gravitation:
Therefore, the weight of an object of mass m in the surface of the earth is obtained by multiplying the mass m by the acceleration of gravity, g, on the surface of the Earth. The acceleration of gravity is approximately the product of the universal gravitational constant G and the mass of the Earth M divided by the radius of the Earth, r squared. (We assume that the earth is spherical and the abandonment of the radius of the object relative to the radius of the Earth in this discussion.) The acceleration of gravity measured on the surface of the Earth is at about 980 cm / second / second.
Mass and Weight
The mass is a measure of the amount of material is on an object, but the weight is a measure of the force of gravity exerted on the material in a gravitational field; therefore, the mass and weight are proportional to each other, with the acceleration due to gravity as the proportionality constant. It follows that the mass is constant for an object (actually this is not entirely true, but we'll save that surprise for our later discussion of the theory of relativity), but the weight depends on the location of the object. For example, if we transport the above object of the mass m of the surface of the Moon, the acceleration of gravity would change because the radius and mass of the Moon, both differ from those on Earth. Therefore, our object has mass m both on the surface of the Earth and on the surface of the moon, but weigh much less on the surface of the moon because the acceleration of gravity is not a factor of 6 less than in the surface of the earth.
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