What is the significance of Newton"s Universal gravity constant ? how is it Universal?
827924
It is called 'universal' because it works for any mass, microscopic or astronomic.
981506
a. The force of the gravitational attraction between two objects is given by the formula\n\nF= G*(M1*M2/R^2)\n\nwhere G is the gravitational constant, M1,M2 are the two masses and R is the distance between their center of masses.\n\nSince the distance between your center of mass and the Earth's center of mass is such a large distance, you can approximate this distance as being the mean, average, radius of the Earth.\n\nG can be easily found in any physics book and you are given everything else. Just plug everything in to the equation and that will give you the gravitational force between you and the Earth.\n\nb. How much you weigh is directly related to the force you just calculated. In fact, they are the same thing. Your weight is a measure of how hard the Earth is pulling you towards its center.\n\nMy old physics professor used to joke that if you want to loose weight just walk up some stairs. Since you can't loose any mass, if you are able to decrease the distance between you and the center of the Earth you will lessen the pull of gravity and thus loose weight.
890942
The gravitational constant is perhaps the most difficult physical constant to measure. In SI units, the 2002 CODATA recommended value of the gravitational constant is\n\n    G = &#92;left(6.6742 &#92;plusmn 0.0010 &#92;right) &#92;times 10^{-11} &#92; &#92;mbox{N} &#92; &#92;mbox{m}^2 &#92; &#92;mbox{kg}^{-2} &#92;,\n\n        = &#92;left(6.6742 &#92;plusmn 0.0010 &#92;right) &#92;times 10^{-11} &#92; &#92;mbox{m}^3 &#92; &#92;mbox{s}^{-2} &#92; &#92;mbox{kg}^{-1} &#92;,\n\nAnother authoritative estimate is given by the International Astronomical Union (see Standish, 1995)\nSo far so good, it works. Therefore it is proven 'Universal'.
112179
Gravity is a force of attraction that acts between bodies that have mass. It is a physical phenomenon of fundamental importance, profoundly affecting the workings of the world around us and the universe beyond. Most familiarly, it is the gravitational attraction of the earth that endows objects with weight and causes them to fall to the ground when dropped. In fact, gravity is also the reason for the very existence of the earth, the sun and other celestial bodies; without it matter would not have coalesced into these bodies and life as we know it would not exist. Gravity is also responsible for keeping the earth and the other planets in their orbits around the sun, the moon in its orbit around the earth, for the tides, and for various other natural phenomena that we observe.\n\nIn common usage "gravity" and "gravitation" are either used interchangeably, or the distinction is sometimes made that "gravity" is specifically the attractive force of the earth, while "gravitation" is the general property of mutual attraction between bodies of matter. In technical usage, "gravitation" is the tendency of bodies to accelerate towards one another, and "gravity" is the force that some theories use to explain this acceleration.\n\nGravity was rather poorly understood until Isaac Newton formulated his law of gravitation in the 17th century. Newton's theory is still widely used for many practical purposes, though for more advanced work it has been supplanted by Einstein's general relativity. While a great deal is now known about the properties of gravity, the ultimate cause of the gravitational force remains an open question and gravity remains an important topic of scientific research.\n\nContents [hide]\n1 Overview of the history of gravitational theory \n2 The Earth's gravity \n2.1 Comparative gravities of the Earth, Sun, Moon and planets \n3 Mathematical equations for a falling body \n3.1 Gravitational potential \n3.2 Acceleration relative to the rotating Earth \n4 Gravity and astronomy \n4.1 Self-gravitating system \n5 Practical uses of gravity \n6 Newton's law of universal gravitation \n6.1 Acceleration due to gravity \n6.2 Bodies with spatial extent \n6.3 Vector form \n6.4 Gravitational field \n7 Problems with Newton's theory \n7.1 Theoretical concerns \n7.2 Disagreement with observation \n7.3 Newton's reservations \n8 Einstein's theory of gravitation \n8.1 Experimental tests \n9 Comparison with electromagnetic force \n10 Gravity and quantum mechanics \n11 Alternative theories \n11.1 Recent alternative theories \n11.2 Historical alternative theories \n12 Notes \n13 See also \n14 References \n15 External links \n \n\n\n[edit]\nOverview of the history of gravitational theory\nThe first mathematical formulation of gravity was Isaac Newton's law of universal gravitation, published in his 1687 work Principia Mathematica. Professor William Whewell of Cambridge University, author of History of the Inductive Sciences (1837) stated:\n\n"The law of gravitation is indisputably and incomparably the greatest scientific discovery ever made, whether we look at the advance which it involved, the extent of the truth disclosed, or the fundamental and satisfactory nature of this truth." [In A Treasury of Science ed. Harlow Shapley et al, Harper & Bros. NY: 1946] \nAlthough the law of universal gravitation was first clearly and rigorously formulated by Isaac Newton, the phenomenon was observed and recorded by others. Even Ptolemy (c. 100-178) had a vague conception of a force tending toward the center of the Earth which not only kept bodies upon its surface, but in some way upheld the order of the universe. Indian astronomer Brahmagupta (598-668), who followed a heliocentric solar system, was the first to recognize gravity as a force of attraction. He explained that "bodies fall towards the Earth as it is in the nature of the Earth to attract bodies
899931
Issac Newton\n\nGallileo however proved that gravitational 'time to fall'was the same for 2 objects of different weights. Gallileo died 11 months before Newton's birth. There work was very complimentary. Newton established the gravitational constant that both backs up Gallileo and demonstrated that it is also gravity that causes the planets to orbit the Sun. The apple under the tree is a bit of a myth!
341512
Newton's laws of motion together with his law of gravity give a relation among\n\n    * the period P of a planet's orbit.\n    * the distance a from the planet to the Sun.\n    * a constant G measured in laboratory experiments.\n    * the mass M of the Sun. \n\n(For our purposes, assume the orbits are circles. Also assume that the mass of a planet is tiny compared to the mass of the Sun.)\n\n\nUsing this relation with P and a for the Earth gives the mass of the Sun.\n\nM ~ 2 x 1030 kg.\n\nWe will use this relation later on to get the masses of other stars.\n\nIt can also be used to get the masses of galaxies!\n\nDavison E. Soper, Institute of Theoretical Science, University of Oregon, Eugene OR 97403 USA soper@bovine.uoregon.edu
158544
hmm....by power I'm pretty sure you are just asking what causes the "attractive force" of gravity? .... the short answer is that matter itself (objects with mass) impose a curvature on the surrounding spacetime which we feel as the attractive force of gravity. \n\nThe more complicated answer is that a quantam theory of gravity would have to be eventually discovered as to make gravity consistent with the other three forces now explained by quantum mechanics..(electromagnetic, weak, strong). Each one of these forces is mediated by an associated particle (electromagnetic- photon, weak-w boson, strong- gluon). The problem is that at the current time no one has ever found the theorized graviton which would be the force mediator for gravity. It has also been speculated that the idea of "mass" is itself mediated by a particle known as the Higgs Boson. This particle along with the graviton would go a long way to explain the most familiar force in our daily lives... but the most mysterious as far as science is concerned.
738834
d is the most correct answer, yes.  \n\nHowever keep in mind that despite g being the "gravitational constant", acceleration caused by gravity DOES change depending on the the distance from the earth.  When we're talking about the difference of a table, there is practically no difference, however keep in mind that it does change.
494757
In I. Newton's time. It was 1805. But I have to find out more.\nIsaac Newton(1642-1726) published the manuscript of Philosophiae naturalis principia mathematica,in April,1686.\nThe law of universal gravitation=\nf=Gmm'/d^2, where G is given as 6.6732*10^(-11) Nm/kg,where N=Newton, a unit for measuring force.\nThe date of publication is not exactly the same date of discovery, normally it is a short time earlier.\nCharles Darwin published his work on evolution, but he had worked on it for 20 some years before his publication. Another man had the same idea about evolution, but only jointly published a short paper with Charles Darwin.\nTherefore, the exact date of discovery of something, is a thesis subject.
916991
The force of gravity is indeed given by Newton's equation:\n\nF = G*M*m/r²\n\nwhere G is the gfravitational constant, M is the mass of the Earth, m is the mass of the space ship and r is the distance between their centers of mass.\n\nThus, if the space ship is 5 Earth radii above the surface of the planet, then it is 6 Earth radii from the planet's center:\n\nr = (6/5) * (32000 km * 1000 m/km) = 38400000 m\n\nThe mass of the Earth is about 5.9742×10^24 kg. Finally, the value of G, the gravitational constant is about 6.6742x10^-11. Substituting these values into Newton's equation provides:\n\nF = (6.6742x10^-11)(5.9742×10^24 kg)(1500 kg) / (38400000 m\n)²\n\nF = 405.61 N
443153
In physics, the graviton is a hypothetical elementary particle that transmits the force of gravity in most quantum gravity systems. In order to do this, one theory posits that gravitons have to be always-attractive (gravity never pushes), work over any distance (gravity is universal) and come in unlimited numbers (to provide high strengths near stars). In quantum theory, these requirements define an even-spin (spin 2 in this case) boson with a rest mass of zero.
58372
the formula you need is Fg=Gm1m2/r^2.  so just plug in. G is the universal gravitational constant. so it's:\n(6.673 x 10^-11)(70)(70)/(1)^2 = 3.327 x 10^-7 N\n\nas you can see, this is negligable because people are not big enough to create a substancial gravitational force.
909451
The energy per unit volume of a gravitational mass is the pressure holding the mass together. so if you multipy the gravitational pressure that hold the mass together by the area enveloping the gravitational mass you obtain the total force surounding the mass.\nAs Sherlock Holmes would say = "elementary...\nTherefore from this analysis we see that The gravitational force is proportional to the curvature of the gravitational mass which in turns causes a curvature of the space gravity field.\nAnd that is the whole principle of gravity.\nIt took me years to figure that one out.
44051
The other posters are correct.  The mass of the object is unchanged.  but, the force of gravity is different on mars.  If you were standing on mars holding the object, mars would be exerting less gravity on the object than earth and thus the object would feel lighter.\n\nNewton determined that the force acting on an object is F=-GMr/r3 \n\nWhere G is the universal gravitation constant = 6.672 e-11 m^3 kg^-1 s^-2 and r is the radius (from the center of the planet) and M is the mass of the planet.  Mars is about one tenth the weight of earth, but it is also much smaller, thus you are closer to the center of mars.  The net effect is that an object feels 0.38 as heavy on mars as it does on earth.
915700
Earth's gravity accelerates objects at a rate of 9.8 m/s/s.  G is the gravitational constant.  You can figure this out by dropping any object, measuring the speed it was moving when it passes a certain point, and how long it took.\n\nForce = G * mass1 * mass2 /distance^2 is the equation that newton came up with explain how gravity worked.\n\nSince the mass of an object on the earth that you would drop to measure this is so small, we can ignore it, so we end up with the equation of \n\n9.8 = (G * Mass of Earth) / (Earth's radius ^2)\n\nThe earth's radius is about 6,360 km.  Convert that into meters and you get 6360000 meters.\n\nThe gravitational constant is a tricky thing to figure out but some guy named Cavendish figured it out.  Read about it http://www.leydenscience.org/physics/gravitation/cavend.htm\n\nNow we know that G = 6.67 x 10^-11 m^3/kg/s^2 so now plug in all the numbers and you get\n\n9.8 = (6.67 x 10^-11 * Earth's Mass) / 6360000^2\n\n6360000^2 = 4.04496 x 10^13\n\nso \n9.8 = (6.67 x 10^-11 * Earth's Mass) / 4.04496 x 10^13\n\nWe want to get Earth's Mass on it's own side so multiply both sides by 4.04496 x 10^13 and you get:\n\n4.04496 x 10^13 * 9.8 = 6.67 x 10^-11 * Earth's Mass\n\nDivide both sides by the gravitational constant of 6.67 x 10^-11 and you get \nEarth's Mass = (4.04496x10^13 * 9.8)/ 6.67 x 10^-11\n\nPlug that all into a scientific calculator and you get for the Earth's mass about\n5.94311964 x 10^24 kilograms\n\nAnd that's how they did it back in the 17th century.  Heh neato I figured out the mass of the earth.  Never did that before.
87660
Any matter with mass also has the property of gravity. There are two basic schools of thought about what gravity itself is. One idea is that the attractive properties of gravity result from two or more chunks of matter exchanging an elementary particle called the "graviton." One example would be the gravitational attraction between the Earth and the Moon---each planet exchanges gravitons. So far, these graviton particles have not been observed.\n\nAnother idea, this one from Einstein's theory of relativity, says that matter (mass) actually bends the fabric of space, sort of like what would happen if you placed a bowling ball on a sheet of thin rubber. The resulting deformation of space by mass results in other objects to follow the shape of the deformed space. In the Earth/Moon example, the Moon orbits around Earth because it's simply following the shape of the wrinkle in space made by Earth's mass.
814715
no. \nthe stress-energy tensor tells us how the energy is spread, and moves, across spacetime.\nthe gravitational constant is a parameter that determines to what degree 1 kg of mass (for instance) will "warp" the spacetime. \n\nso, you can't derive it from the einstein equation.\n\nin fact, relativists usually set the gravitational constant to = 1, so that they don't have to deal with it. although it's essential when you're trying to determine exactly what your physical predictions will be, it's not really an active element of einstein's theory. it just kind of sits there.