The acceleration due to gravity at the Earth's surface, denoted g, is approximately 9.8 m/s2 (metres per second squared) or 32 ft/sec2. This means that, ignoring air resistance, an object falling freely near the earth's surface increases in speed by 9.8 m/s (around 22 mph) for each second of its descent. Thus, an object starting from rest will attain a speed of 9.8 m/s after one second, 19.6 m/s after two seconds, and so on. The earth itself experiences an equal and opposite force to that of the falling object, m ...

See also:

Gravity, Gravity - Overview of the history of gravitational theory, Gravity - Newton's law of universal gravitation, Gravity - Acceleration due to gravity, Gravity - Bodies with spatial extent, Gravity - Vector form, Gravity - Gravitational field, Gravity - The Earth's gravity, Gravity - Comparative gravities of the Earth Sun Moon and planets, Gravity - Mathematical equations for a falling body, Gravity - Gravitational potential, Gravity - Acceleration relative to the rotating Earth, Gravity - Gravity and astronomy, Gravity - Self-gravitating system, Gravity - Practical uses of gravity, Gravity - Problems with Newton's theory, Gravity - Theoretical concerns, Gravity - Disagreement with observation, Gravity - Newton's reservations, Gravity - Einstein's theory of gravitation, Gravity - Experimental tests, Gravity - Comparison with electromagnetic force, Gravity - Gravity and quantum mechanics, Gravity - Alternative theories, Gravity - Recent alternative theories, Gravity - Historical alternative theories, Gravity - Notes

Read more here: » Gravity: Encyclopedia II - Gravity - The Earth's gravity

See also:

Gravity, Gravity - Overview of the history of gravitational theory, Gravity - The Earth's gravity, Gravity - Comparative gravities of the Earth Sun Moon and planets, Gravity - Mathematical equations for a falling body, Gravity - Gravitational potential, Gravity - Acceleration relative to the rotating Earth, Gravity - Gravity and astronomy, Gravity - Self-gravitating system, Gravity - Practical uses of gravity, Gravity - Newton's law of universal gravitation, Gravity - Acceleration due to gravity, Gravity - Bodies with spatial extent, Gravity - Vector form, Gravity - Gravitational field, Gravity - Problems with Newton's theory, Gravity - Theoretical concerns, Gravity - Disagreement with observation, Gravity - Newton's reservations, Gravity - Einstein's theory of gravitation, Gravity - Experimental tests, Gravity - Comparison with electromagnetic force, Gravity - Gravity and quantum mechanics, Gravity - Alternative theories, Gravity - Recent alternative theories, Gravity - Historical alternative theories, Gravity - Notes

Read more here: » Gravity: Encyclopedia II - Gravity - The Earth's gravity

Thee acceleration due to gravity at the Earth's surface, denoted g, is approximately 9.8 m/s2 (metres per second squared) or 32 ft/sec2. This means that, ignoring air resistance, an object falling freely near the earth's surface increases in speed by 9.8 m/s (around 22 mph) for each second of its descent. Thus, an object starting from rest will attain a speed of 9.8 m/s after one second, 19.6 m/s after two seconds, and so on. The earth itself experiences an equal and opposite force to that of the falling object, ...

See also:

Gravity, Gravity - Overview of the history of gravitational theory, Gravity - Newton's law of universal gravitation, Gravity - Acceleration due to gravity, Gravity - Bodies with spatial extent, Gravity - Vector form, Gravity - Gravitational field, Gravity - The Earth's gravity, Gravity - Comparative gravities of the Earth Sun Moon and planets, Gravity - Mathematical equations for a falling body, Gravity - Gravitational potential, Gravity - Acceleration relative to the rotating Earth, Gravity - Gravity and astronomy, Gravity - Self-gravitating system, Gravity - Practical uses of gravity, Gravity - Problems with Newton's theory, Gravity - Theoretical concerns, Gravity - Disagreement with observation, Gravity - Newton's reservations, Gravity - Einstein's theory of gravitation, Gravity - Experimental tests, Gravity - Comparison with electromagnetic force, Gravity - Gravity and quantum mechanics, Gravity - Alternative theories, Gravity - Recent alternative theories, Gravity - Historical alternative theories, Gravity - Notes

Read more here: » Gravity: Encyclopedia II - Gravity - The Earth's gravity

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 ...

Including:

• Gravity - Overview of the history of gravitational theory
• Gravity - Newton's law of universal gravitation
• Gravity - Acceleration due to gravity
• Gravity - Bodies with spatial extent
• Gravity - Vector form
• Gravity - Gravitational field
• Gravity - The Earth's gravity
• Gravity - Comparative gravities of the Earth Sun Moon and planets
• Gravity - Mathematical equations for a falling body
• Gravity - Gravitational potential
• Gravity - Acceleration relative to the rotating Earth
• Gravity - Gravity and astronomy
• Gravity - Self-gravitating system
• Gravity - Practical uses of gravity
• Gravity - Problems with Newton's theory
• Gravity - Theoretical concerns
• Gravity - Disagreement with observation
• Gravity - Newton's reservations
• Gravity - Einstein's theory of gravitation
• Gravity - Experimental tests
• Gravity - Comparison with electromagnetic force
• Gravity - Gravity and quantum mechanics
• Gravity - Alternative theories
• Gravity - Recent alternative theories
• Gravity - Historical alternative theories
• Gravity - Notes

Read more here: » Gravity: Encyclopedia - Gravity

The Aristotelian theory of gravity was that all bodies move towards their natural place. For some objects, Aristotle claimed the natural place to be the center of the earth, wherefore they fall towards it. For other objects, the natural place is the heavenly spheres, wherefore gases, steam for example, move away from the center of the earth and towards heaven and to the moon. The speed of th ...

Read more here: » Aristotelian theory of gravity: Encyclopedia - Aristotelian theory of gravity

In physics, the center of gravity (CG) of an object is a point at which the object's mass can be assumed, for many purposes, to be concentrated. For example, if you hang an object from a string, the object's center of gravity will be directly below the string. The path of an object in orbit depends only on its center of gravity. In objects that are radially symmetric, both the center of gravity and the center of mass coincide. The center of gravity of an object is the average location of its weight. In a uniform gravitation ...

Including:

• Center of gravity - Centers of gravity of simple objects
• Center of gravity - Locating Center of Gravity 1
• Center of gravity - Locating Center of Gravity 2
• Center of gravity - Similarities between center of mass and center of inertia
• Center of gravity - Differences between center of mass and center of inertia

Read more here: » Center of gravity: Encyclopedia - Center of gravity

Anti-gravity is a hypothetical means of countering or otherwise modifying the effects of gravity, typically in the context of spacecraft propulsion. Such systems are limited to the realm of science fiction given the current understanding of the way gravity works, but this has not stopped legions of hopefuls from making various spinning disks and magnets in hopes of perfecting such a device. Anti-gravity - Anti-gravity in the context of mainstream physics. Newton's Law of Gravitation cons ...

Including:

• Anti-gravity - Anti-gravity in the context of mainstream physics
• Anti-gravity - Conventional effects that look like anti-gravity
• Anti-gravity - Anti-gravity in the context of non-mainstream physics

Read more here: » Anti-gravity: Encyclopedia - Anti-gravity

API Gravity is a specific gravity scale developed by the American Petroleum Institute (API) for measuring the relative density of various petroleum liquids. API gravity is gradated in degrees on a hydrometer instrument and was designed so that most values would fall between 10 and 70 API gravity degrees. The U.S. National Bureau of Standards established the Baumé scale (see degrees Baumé) as the standard for measuring specific gravity of liquids less dense than water in 1916. Investigation by the U.S. National A ...

Read more here: » API gravity: Encyclopedia - API gravity

The Rev. Dr. Sun Myung Moon (born January 6, 1920) is the founder of the Family Federation for World Peace and Unification, first established as the Unification Church on May 1, 1954, in Seoul, South Korea. With his wife Hak Ja Han, he is co-leader of the Unification Movement. Rev. Moon's followers regard him and his wife as "the True Parents of humankind" and hail him as the Messiah. Sun Myung Moon - Name and forms of address. The Hanja for "Moon" (문, 文), the reverend's surname, means "word" or "truth" ...

Including:

• Sun Myung Moon - Name and forms of address
• Sun Myung Moon - Biography
• Sun Myung Moon - Life in Korea
• Sun Myung Moon - Marriage
• Sun Myung Moon - Views on Communism
• Sun Myung Moon - Leading the Unification Church overseas
• Sun Myung Moon - Arrival in the United States
• Sun Myung Moon - 1980s
• Sun Myung Moon - 1990s
• Sun Myung Moon - 2000s
• Sun Myung Moon - General criticism
• Sun Myung Moon - Prison terms
• Sun Myung Moon - Other issues

Read more here: » Sun Myung Moon: Encyclopedia - Sun Myung Moon

The Moon as seen from Earth Ammonia Carbon dioxide The Moon is the planet Earth's only natural satellite. It has no formal name other than "The Moon", although in English it is occasionally called Luna (Latin for moon), or Selene, to distinguish it from the generic "moon" (natural satellites of other planets are also called moons). Its symbol is a crescent (Unicode: ☾). The terms lunar, selene/seleno-, and cynthion (from the Lunar deities Selene and Cynthia) refer to the Moon (apo ...

Including:

• Moon - The two sides
• Moon - Orbit
• Moon - Earth & Moon
• Moon - Origin and history
• Moon - Physical characteristics
• Moon - Composition
• Moon - Selenography
• Moon - Presence of water
• Moon - Magnetic field
• Moon - Atmosphere
• Moon - Eclipses
• Moon - Occultation of stars
• Moon - Observation of the Moon
• Moon - Exploration of the Moon
• Moon - Human understanding of the Moon
• Moon - Myth and folk culture
• Moon - The Moon as muse
• Moon - Astrology
• Moon - Scientific understanding
• Moon - Meteor impact on the Moon
• Moon - Legal status
• Moon - Satellites
• Moon - Surface installations
• Moon - Lunar location listings

Read more here: » Moon: Encyclopedia - Moon

(332,950 Earths) (27.9 g) The Sun (or Sol) is the star at the center of our Solar system. Earth orbits the Sun, as do many other bodies, including other planets, asteroids, meteoroids, comets and dust. Its heat and light support almost all life on Earth. The Sun is a ball of plasma with a mass of about 2×1030 kg, which is somewhat higher than that of an average star. About 74% of its mass is hydrogen, with 25% helium and the rest made up of trace quantities of heavier elements. It is thou ...

Including:

• Sun - General information
• Sun - Structure
• Sun - Core
• Sun - Radiation zone
• Sun - Convection zone
• Sun - Photosphere
• Sun - Temperature minimum
• Sun - Chromosphere
• Sun - Corona
• Sun - Theoretical problems
• Sun - Solar neutrino problem
• Sun - Coronal heating problem
• Sun - Faint young sun problem
• Sun - Magnetic field
• Sun - Position of the Sun through the year
• Sun - Solar space missions
• Sun - History and future of the Sun
• Sun - Human understanding of the Sun
• Sun - The Sun as a power source
• Sun - Sun and eye damage

Read more here: » Sun: Encyclopedia - Sun

Earth, also known as Terra, and Tellus mostly in the 19th century, is the third-closest planet to the Sun. It is the largest of the solar system's terrestrial planets, and the only planetary body that modern science confirms as harboring life. Scientific evidence indicates that the planet formed around 4.57 billion (4.57×109) years ago, and shortly thereafter (4.533 billion years ago) acquired its single natural satellite, the Moon. Earth - Lexicography. Its astronomical symbol con ...

Including:

• Earth - Lexicography
• Earth - Physical characteristics
• Earth - Earth in the solar system
• Earth - The Moon
• Earth - Geography
• Earth - Environment and Ecosystem
• Earth - Climate
• Earth - Terrain
• Earth - Natural resources
• Earth - Land use
• Earth - Natural and environmental hazards
• Earth - Human geography
• Earth - Descriptions of Earth

Read more here: » Earth: Encyclopedia - Earth

The actual acceleration of a body at the Earth's surface depends on the location at which it is measured, smaller at lower latitudes, for two reasons. The first is that the rotation of the Earth imposes an additional acceleration on the body that opposes gravitational acceleration. The net downward force on the body is therefore offset by a centrifugal force that acts upwards, reducing its weight. This effect on its own would result in a range of values of g from 9. ...

See also:

Gee, Gee - Variations of Earth's gravity, Gee - Calculated value of g, Gee - Usage of the unit, Gee - Human g-force experience, Gee - Strongest g-forces survived by humans, Gee - Reference

Read more here: » Gee: Encyclopedia II - Gee - Variations of Earth's gravity

LeSage realized that the interactions between the gravitational particles and ordinary matter must be inelastic, that is, the particles must lose energy in the process. Without this, the net force on the object would be zero. However, if the particles lose energy, then the material object must gain this energy in order to satisfy conservation of energy. If this energy is converted to heat calculations done in the 19th century indicated that in order for the Earth to remain in orbit around the Sun, this energy transfer would result in the pla ...

See also:

LeSage gravity, LeSage gravity - LeSage's theory, LeSage gravity - Objections to the theory, LeSage gravity - Recent attempts at a revival, LeSage gravity - Reference

Read more here: » LeSage gravity: Encyclopedia II - LeSage gravity - Objections to the theory

Moon - Tidal Effects. The tides on Earth are generated by the Moon's gravitation (see tide and tidal force for a more detailed discussion). There are two tidal bulges, one in the direction of the Moon, and one in the opposite direction (figure 1). The buildup of these bulges and their movement around the earth causes an energy loss due to friction. The energy loss decr ...

See also:

Moon, Moon - The two sides of the Moon, Moon - Orbit, Moon - Earth & Moon, Moon - Tidal Effects, Moon - Double-planet hypotheses, Moon - Origin and history, Moon - Physical characteristics, Moon - Composition, Moon - Selenography, Moon - Presence of water, Moon - Magnetic field, Moon - Atmosphere, Moon - Eclipses, Moon - Occultation of stars, Moon - Observation of the Moon, Moon - Exploration of the Moon, Moon - Human understanding of the Moon, Moon - Myth and folk culture, Moon - The Moon as muse, Moon - Astrology, Moon - Scientific understanding, Moon - Meteor impact on the Moon, Moon - Legal status, Moon - Satellites, Moon - Surface installations, Moon - Lunar location listings

Read more here: » Moon: Encyclopedia II - Moon - Earth & Moon

Artificial gravity could be created in several ways: Artificial gravity - Rotation. The spacecraft could rotate so that anything inside will be forced toward the outside by centrifugal force. Artificial gravity by rotation has the following side effects: Coriolis forces produced by rotation could cause dizziness, nausea and disorientation. Experiments have shown that slower rates of rotation reduce the Coriolis forces and its effects. It is generally believed that at 2 rpm or less no adverse e ...

See also:

Artificial gravity, Artificial gravity - Methods, Artificial gravity - Rotation, Artificial gravity - Acceleration, Artificial gravity - Mass, Artificial gravity - Tidal forces, Artificial gravity - Magnetism, Artificial gravity - Fiction, Artificial gravity - Rotational Gravity, Artificial gravity - Field generators

Read more here: » Artificial gravity: Encyclopedia II - Artificial gravity - Methods

Some models of anti-gravity claim to derive from general relativity. The model of gravity proposed by the theory of general relativity breaks down under extreme conditions (too far inside a black hole, and in the very early life of the universe under the big bang model). In particular, most physicists believe that at extremely high energies, gravity and the other fundamental forces unify, which would allow gravity to be manipulated in ways that are not readily apparent now. Candidate models for this regime are theories of everyt ...

See also:

Anti-gravity, Anti-gravity - Anti-gravity in the context of mainstream physics, Anti-gravity - Conventional effects that look like anti-gravity, Anti-gravity - Anti-gravity in the context of non-mainstream physics

Read more here: » Anti-gravity: Encyclopedia II - Anti-gravity - Anti-gravity in the context of mainstream physics

There are a number of proposed quantum gravity theories: String theory/superstring theory/M-theory Supergravity AdS/CFT Wheeler-deWitt equation Loop quantum gravity Euclidean quantum gravity Noncommutative geometry Twistor theory Discrete Lorentzian quantum gravity Sakharov induced gravity Regge calculus acoustic metric and other analog model ...

See also:

Quantum gravity, Quantum gravity - Overview, Quantum gravity - Historical perspective, Quantum gravity - The incompatibility of quantum mechanics and general relativity, Quantum gravity - Theories, Quantum gravity - Weinberg-Witten theorem, Quantum gravity - Quantum gravity theorists, Quantum gravity - In Popular Culture

Read more here: » Quantum gravity: Encyclopedia II - Quantum gravity - Theories

Loop quantum gravity - Loop quantization. At the core of loop quantum gravity is a framework for nonperturbative quantization of diffeomorphism-invariant gauge theories, which one might call loop quantization. While originally developed in order to quantize vacuum general relativity in 3+1 dimensions, the formalism can accommodate arbitrary spacetime dimensionalities, fermions (John Baez and Kirill Krasnov), an arbitrary gauge group (or even quantum group), and supersymmetry (Smolin), and results in a quantizatio ...

See also:

Loop quantum gravity, Loop quantum gravity - Loop quantum gravity in general and its ambitions, Loop quantum gravity - The incompatibility between quantum mechanics and general relativity, Loop quantum gravity - History of LQG, Loop quantum gravity - The ingredients of loop quantum gravity, Loop quantum gravity - Loop quantization, Loop quantum gravity - Lorentz invariance, Loop quantum gravity - Diffeomorphism invariance and background independence, Loop quantum gravity - Problems, Loop quantum gravity - Bibliography

Read more here: » Loop quantum gravity: Encyclopedia II - Loop quantum gravity - The ingredients of loop quantum gravity

Gravity Probe B is a relativity gyroscope experiment funded by NASA. Efforts are being headed up by the Physics department at Stanford University with Lockheed Martin as the primary subcontractor. According to mission plans, it will test two unverified predictions of general relativity: The experiment plans to check, very precisely, tiny changes in the direction of spin of four gyroscopes contained in an Earth satellite orbiting at 650 km (400 statute miles, 350 nautical miles) altitude and crossing directly over the poles. So ...

See also:

Gravity Probe B, Gravity Probe B - Overview, Gravity Probe B - Experimental setup, Gravity Probe B - Mission progress, Gravity Probe B - History

Read more here: » Gravity Probe B: Encyclopedia II - Gravity Probe B - Overview