3 laws of gravity essay
As a member, you'll also get unlimited access to over 79, lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed. Already registered? Log in here for access. Log in or sign up to add this lesson to a Custom Course.
Newton's Universal Law of Gravitation
Gravity from Latin gravitas , meaning 'weight' [1] , or gravitation , is a natural phenomenon by which all things with mass or energy —including planets , stars , galaxies , and even light [2] —are brought toward or gravitate toward one another. On Earth , gravity gives weight to physical objects , and the Moon 's gravity causes the ocean tides.
The gravitational attraction of the original gaseous matter present in the Universe caused it to begin coalescing and forming stars and caused the stars to group together into galaxies, so gravity is responsible for many of the large-scale structures in the Universe. Gravity has an infinite range, although its effects become increasingly weaker as objects get further away. Gravity is most accurately described by the general theory of relativity proposed by Albert Einstein in , which describes gravity not as a force , but as a consequence of the curvature of spacetime caused by the uneven distribution of mass.
The most extreme example of this curvature of spacetime is a black hole , from which nothing—not even light—can escape once past the black hole's event horizon. Gravity is the weakest of the four fundamental interactions of physics, approximately 10 38 times weaker than the strong interaction , 10 36 times weaker than the electromagnetic force and 10 29 times weaker than the weak interaction.
As a consequence, it has no significant influence at the level of subatomic particles. The ancient Greek philosopher Archimedes discovered the center of gravity of a triangle. The Roman architect and engineer Vitruvius in De Architectura postulated that gravity of an object did not depend on weight but its "nature".
In ancient India, Aryabhata first identified the force to explain why objects are not thrown outward as the earth rotates.
Brahmagupta described gravity as an attractive force and used the term "gurutvaakarshan" for gravity. Modern work on gravitational theory began with the work of Galileo Galilei in the late 16th and early 17th centuries. In his famous though possibly apocryphal [11] experiment dropping balls from the Tower of Pisa , and later with careful measurements of balls rolling down inclines , Galileo showed that gravitational acceleration is the same for all objects.
This was a major departure from Aristotle 's belief that heavier objects have a higher gravitational acceleration. Galileo's work set the stage for the formulation of Newton's theory of gravity. In , English mathematician Sir Isaac Newton published Principia , which hypothesizes the inverse-square law of universal gravitation.
In his own words, "I deduced that the forces which keep the planets in their orbs must [be] reciprocally as the squares of their distances from the centers about which they revolve: and thereby compared the force requisite to keep the Moon in her Orb with the force of gravity at the surface of the Earth; and found them answer pretty nearly.
Where F is the force, m 1 and m 2 are the masses of the objects interacting, r is the distance between the centers of the masses and G is the gravitational constant. Newton's theory enjoyed its greatest success when it was used to predict the existence of Neptune based on motions of Uranus that could not be accounted for by the actions of the other planets.
A discrepancy in Mercury 's orbit pointed out flaws in Newton's theory. By the end of the 19th century, it was known that its orbit showed slight perturbations that could not be accounted for entirely under Newton's theory, but all searches for another perturbing body such as a planet orbiting the Sun even closer than Mercury had been fruitless. The issue was resolved in by Albert Einstein 's new theory of general relativity , which accounted for the small discrepancy in Mercury's orbit.
This discrepancy was the advance in the perihelion of Mercury of Although Newton's theory has been superseded by Albert Einstein 's general relativity, most modern non-relativistic gravitational calculations are still made using Newton's theory because it is simpler to work with and it gives sufficiently accurate results for most applications involving sufficiently small masses, speeds and energies.
The simplest way to test the weak equivalence principle is to drop two objects of different masses or compositions in a vacuum and see whether they hit the ground at the same time. Such experiments demonstrate that all objects fall at the same rate when other forces such as air resistance and electromagnetic effects are negligible. Satellite experiments, for example STEP , are planned for more accurate experiments in space.
In general relativity , the effects of gravitation are ascribed to spacetime curvature instead of a force. The starting point for general relativity is the equivalence principle , which equates free fall with inertial motion and describes free-falling inertial objects as being accelerated relative to non-inertial observers on the ground.
Einstein proposed that spacetime is curved by matter, and that free-falling objects are moving along locally straight paths in curved spacetime.
These straight paths are called geodesics. Like Newton's first law of motion, Einstein's theory states that if a force is applied on an object, it would deviate from a geodesic. For instance, we are no longer following geodesics while standing because the mechanical resistance of the Earth exerts an upward force on us, and we are non-inertial on the ground as a result. This explains why moving along the geodesics in spacetime is considered inertial.
Einstein discovered the field equations of general relativity, which relate the presence of matter and the curvature of spacetime and are named after him. The Einstein field equations are a set of 10 simultaneous , non-linear , differential equations.
The solutions of the field equations are the components of the metric tensor of spacetime. A metric tensor describes a geometry of spacetime. The geodesic paths for a spacetime are calculated from the metric tensor. The tests of general relativity included the following: [21]. An open question is whether it is possible to describe the small-scale interactions of gravity with the same framework as quantum mechanics. General relativity describes large-scale bulk properties whereas quantum mechanics is the framework to describe the smallest scale interactions of matter.
Without modifications these frameworks are incompatible. One path is to describe gravity in the framework of quantum field theory , which has been successful to accurately describe the other fundamental interactions. The electromagnetic force arises from an exchange of virtual photons , where the QFT description of gravity is that there is an exchange of virtual gravitons. However, this approach fails at short distances of the order of the Planck length , [29] where a more complete theory of quantum gravity or a new approach to quantum mechanics is required.
Every planetary body including the Earth is surrounded by its own gravitational field, which can be conceptualized with Newtonian physics as exerting an attractive force on all objects. Assuming a spherically symmetrical planet, the strength of this field at any given point above the surface is proportional to the planetary body's mass and inversely proportional to the square of the distance from the center of the body.
The strength of the gravitational field is numerically equal to the acceleration of objects under its influence. The standard value of 9. Assuming the standardized value for g and ignoring air resistance, this means that an object falling freely near the Earth's surface increases its velocity by 9. Thus, an object starting from rest will attain a velocity of 9. Also, again ignoring air resistance, any and all objects, when dropped from the same height, will hit the ground at the same time.
According to Newton's 3rd Law , the Earth itself experiences a force equal in magnitude and opposite in direction to that which it exerts on a falling object. This means that the Earth also accelerates towards the object until they collide. Because the mass of the Earth is huge, however, the acceleration imparted to the Earth by this opposite force is negligible in comparison to the object's.
If the object does not bounce after it has collided with the Earth, each of them then exerts a repulsive contact force on the other which effectively balances the attractive force of gravity and prevents further acceleration. The force of gravity on Earth is the resultant vector sum of two forces: [38] a The gravitational attraction in accordance with Newton's universal law of gravitation, and b the centrifugal force, which results from the choice of an earthbound, rotating frame of reference.
The force of gravity is weakest at the equator because of the centrifugal force caused by the Earth's rotation and because points on the equator are furthest from the center of the Earth. The force of gravity varies with latitude and increases from about 9. This resulting force is the object's weight. The acceleration due to gravity is equal to this g. An initially stationary object which is allowed to fall freely under gravity drops a distance which is proportional to the square of the elapsed time.
The image on the right, spanning half a second, was captured with a stroboscopic flash at 20 flashes per second. This expression is valid only over small distances h from the surface of the Earth. The application of Newton's law of gravity has enabled the acquisition of much of the detailed information we have about the planets in the Solar System, the mass of the Sun, and details of quasars ; even the existence of dark matter is inferred using Newton's law of gravity.
Although we have not traveled to all the planets nor to the Sun, we know their masses. These masses are obtained by applying the laws of gravity to the measured characteristics of the orbit.
In space an object maintains its orbit because of the force of gravity acting upon it. Planets orbit stars, stars orbit galactic centers , galaxies orbit a center of mass in clusters, and clusters orbit in superclusters. The force of gravity exerted on one object by another is directly proportional to the product of those objects' masses and inversely proportional to the square of the distance between them. General relativity predicts that energy can be transported out of a system through gravitational radiation.
Any accelerating matter can create curvatures in the space-time metric, which is how the gravitational radiation is transported away from the system. Co-orbiting objects can generate curvatures in space-time such as the Earth-Sun system, pairs of neutron stars, and pairs of black holes.
Another astrophysical system predicted to lose energy in the form of gravitational radiation are exploding supernovae. The first indirect evidence for gravitational radiation was through measurements of the Hulse—Taylor binary in This system consists of a pulsar and neutron star in orbit around one another.
Its orbital period has decreased since its initial discovery due to a loss of energy, which is consistent for the amount of energy loss due to gravitational radiation. This research was awarded the Nobel Prize in Physics in The first direct evidence for gravitational radiation was measured on 14 September by the LIGO detectors. The gravitational waves emitted during the collision of two black holes 1. It also opens the way for practical observation and understanding of the nature of gravity and events in the Universe including the Big Bang.
As of [update] , the gravitational radiation emitted by the Solar System is far too small to measure with current technology. In December , a research team in China announced that it had produced measurements of the phase lag of Earth tides during full and new moons which seem to prove that the speed of gravity is equal to the speed of light.
The team's findings were released in the Chinese Science Bulletin in February In October , the LIGO and Virgo detectors received gravitational wave signals within 2 seconds of gamma ray satellites and optical telescopes seeing signals from the same direction. This confirmed that the speed of gravitational waves was the same as the speed of light. There are some observations that are not adequately accounted for, which may point to the need for better theories of gravity or perhaps be explained in other ways.
From Wikipedia, the free encyclopedia. Attractive force between objects with mass. For other uses, see Gravity disambiguation. For other uses, see Gravitation disambiguation and Law of Gravity disambiguation. Second law of motion. History Timeline. Newton's laws of motion. Analytical mechanics Lagrangian mechanics Hamiltonian mechanics Routhian mechanics Hamilton—Jacobi equation Appell's equation of motion Koopman—von Neumann mechanics.
Core topics. Circular motion Rotating reference frame Centripetal force Centrifugal force reactive Coriolis force Pendulum Tangential speed Rotational speed.
Newton's law of gravitation, statement that any particle of matter in the universe attracts any the work in which the physicist introduced his three laws of motion. 3. To every action, there is an equal and opposite reaction, i.e. forces are mutual. A more useful equivalent statement is that interacting objects.
Newton's law of universal gravitation is usually stated as that every particle attracts every other particle in the universe with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. This is a general physical law derived from empirical observations by what Isaac Newton called inductive reasoning. When Newton presented Book 1 of the unpublished text in April to the Royal Society , Robert Hooke made a claim that Newton had obtained the inverse square law from him.
Isaac Newton was born in and became famous for his work on gravity and his three laws of motion.
Isaac Newton was a physicist and mathematician who developed the principles of modern physics, including the laws of motion and is credited as one of the great minds of the 17th-century Scientific Revolution. In , he published his most acclaimed work, Philosophiae Naturalis Principia Mathematica Mathematical Principles of Natural Philosophy , which has been called the single most influential book on physics. Newton was born on January 4, , in Woolsthorpe, Lincolnshire, England.
Sir Isaac Newton
As a member, you'll also get unlimited access to over 79, lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed. Already registered? Log in here for access. Log in or sign up to add this lesson to a Custom Course.
Newton's law of universal gravitation
Newton's Laws of Motion help us to understand how objects behave when they are standing still; when they are moving, and when forces act upon them. There are three laws of motion. Newton's First Law of Motion states that an object in motion tends to stay in motion unless an external force acts upon it. Similarly, if the object is at rest, it will remain at rest unless an unbalanced force acts upon it. Basically, what Newton's First Law is saying is that objects behave predictably. If a ball is sitting on your table, it isn't going to start rolling or fall off the table unless a force acts upon it to cause it to do so. Moving objects don't change their direction unless a force causes them to move from their path. As you know, if you slide a block across a table, it eventually stops rather than continuing on forever. This is because the frictional force opposes the continued movement.
Gravity from Latin gravitas , meaning 'weight' [1] , or gravitation , is a natural phenomenon by which all things with mass or energy —including planets , stars , galaxies , and even light [2] —are brought toward or gravitate toward one another. On Earth , gravity gives weight to physical objects , and the Moon 's gravity causes the ocean tides.
Sir Isaac Newton's three laws of motion describe the motion of massive bodies and how they interact. While Newton's laws may seem obvious to us today, more than three centuries ago they were considered revolutionary.
Newton's Laws of Motion
It describes why that apple fell from that tree in that orchard in Lincolnshire. Whether or not that apple actually landed on Isaac Newton's head, as some stories would have it, this equation describes why you stay rooted to the ground, what locks the Earth in orbit around the sun and was used by Nasa engineers to send men to the moon. It encapsulates the idea that all the particles of matter in the universe attract each other through the force of gravity — Newton's law tells us how strong that attraction is. The equation says that the force F between two objects is proportional to the product of their masses m 1 and m 2 , divided by the square of the distance between them. The remaining term in the equation, G, is the gravitational constant, which has to be measured by experiment and, as of , US scientists have measured it at 6. Newton came to the formula after studying the centuries of measurements from astronomers before him. Stargazers had spent millennia cataloguing the positions of the stars and planets in the night sky and, by the 17th century, the German astronomer and mathematician Johannes Kepler had worked out the geometry of these movements. By looking at the movement of Mars, Kepler had calculated that planets orbited the sun in elliptical paths and, in a kind of celestial clockwork, his three laws of planetary motion allowed astronomers to work out the position of the planets in the future based on data from past records. Kepler's laws explain how the planets moved around the sun but not why. Newton filled in that gap by supposing there was a force acting between the bodies that were moving around each other. The story goes that Newton saw an apple fall to the ground and it made him wonder why the fruit always fell straight to the ground; why did it not veer off to the left or right? According to his own laws of motion, anything that begins moving from a standing start is undergoing acceleration and, where there is acceleration, there must be a force. The apple started in the tree and landed on the Earth, which means there must be a force of attraction between the apple and the Earth. And even if the apple were higher up in the tree, it would still feel this force of attraction with the Earth, reasoned Newton.
What Are Newton's Laws of Motion?
Isaac Newton put forward the law in and used it to explain the observed motions of the planets and their moons, which had been reduced to mathematical form by Johannes Kepler early in the 17th century. Newton's law of gravitation. Article Media. Info Print Cite. Submit Feedback. Thank you for your feedback. Home Science Astronomy. See Article History. Read More on This Topic. Newton discovered the relationship between the motion of the Moon and the motion of a body falling freely on Earth.
