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# Gravity

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on 4 September 2012

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#### Transcript of Gravity

GRAVITY What is gravity? Gravity is a force of attraction pulling together all matter. The more matter, the more gravity. Mass is how we measure
the amount
of matter in something. This force is dependent on three factors: The mass of the massive object The mass of the
smaller body The separation between the two,
measured between their geometrical centers. Gravitation is responsible
for various phenomena
observed on Earth for the formation of tides. for heating the interiors of
forming stars and planets. keeping the Earth and the other planets in their orbits around the Sun. Newton’s Law of
Universal Gravitation
Two bodies attract each other with equal and opposite forces Born December 25th , 1642 He was a scientist who combine ideas
to explain how the universe operates Newton used Galileo's ideas and further explained them The idea of gravity was Introduced by Sir Isaac Newton in the late 1600’s How he discovered it ? Newton’s law of Gravitation was discovered while he watched an apple fall from a tree He said that the force that pulled the apple to the ground was the same force, gravitational force, that keeps the moon and earth in it’s orbit Universal Gravitation Newton’s idea was that gravity was a universal force acting between any two objects. When thinking about the apple falling from the tree he wondered if the same principle of gravity could be used outside of earth. He calculated the force needed to keep the moon moving in orbit around the earth. Law
of
Universal
Gravitation In symbols, Newton’s Law of Universal Gravitation is: Where G is a constant of proportionality. Newton concluded that the gravitational force is: Directly proportional to the masses of both objects.
Inversely proportional to the distance between the objects. What is it used for? Gravity keeps us grounded

Astronomers find out other planet’s gravity so then satellites can be put into their orbit. The magnitude of this force is proportional to the product of the two masses and is also proportional to the inverse square of the two bodies. Equivalence Principle The Einstenian equivalence principle The strong equivalence principle The weak equivalence principle Relativity theory Albert Einstein Special Theory of Relativity General Theory of Relativity Gravity
and Quantum Mechanics Is the body of scientific principles that explains the behavior of matter and its interactions with energy on the scale of atoms and atomic particles.
Is an overall term for theories that attempt to unify gravity with the other fundamental forces of physics (which are already unified together).
What is Quantum Mechanics? The strong nuclear force
The weak nuclear force
The electromagnetic force
Gravity finally starts cooperating with quantum mechanics…maybe Gravity is usually the arch-nemesis of quantum mechanics, stubbornly refusing to play nice with the forces governing the interactions of subatomic particles. Now has been discovered a rare instance where gravity actually assists quantum interactions, which just might help unify physics.
Earth’s Gravity It refers to the acceleration that the Earth imparts to objects on or near its surface. This acceleration is measured in meters per second squared or equivalently in newtons per kilogram.
It has an approximate value of 9.81 m/s2 which means that, ignoring the effects of air resistance, the speed of an object falling freely near the Earth’s surface will increase by about 9.81 meters per second every second.
There is a direct relationship between gravitational acceleration and the downwards weight force experienced by objects on Earth. Given by the equation F=ma (force=mass x acceleration)
A perfect sphere of spherically uniform density would produce a gravitational field of uniform magnitude at all points on its surface, always pointing directly towards the sphere's centre. The Earth deviates slightly from this ideal, and there are consequently slight deviations in both the magnitude and direction of gravity across its surface.
Force exerted on an object due to the Earth, called "effective gravity" or "apparent gravity", varies due to the presence of other factors.

Parameters affecting the apparent or actual strength of Earth's gravity include latitude, altitude, and the local topography and geology. The differences of Earth's gravity around the Antarctic continent. Latitude Altitude Local variations in topography cause fluctuations in the Earth's gravitational field, known as gravitational anomalies.
Comparative gravities of the Earth, Sun, Moon, and some planets Gravity anomalies Free-air or Faye’s anomaly
Isostasy Bouguer anomaly
Full transcript