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Explanation of Overview of Gravitation - Succeed in Understanding Physics. Also refer to Law of Universal Gravitation, Isaac Newton, matter, attraction, force, mass, gravity, Einstein, relativity, dark matter, quantum mechanics, fundamental forces, physical science, Ron Kurtus, School for Champions. Copyright © Restrictions
Overview of Gravitation
by Ron Kurtus (revised 22 January 2010)
Gravitation is the attraction between objects because of their mass. Objects can range in size from sub-atomic particles to celestial masses, such as planets, stars and galaxies. Other properties of gravitation include attraction to the center or mass, escape velocity and gravity.
The concept of that matter attracts other objects was formulated by Isaac Newton as the Law of Universal Gravitation. This theory has been superseded by newer theories of gravitation, such as Albert Einstein’s Theory of General Relativity and the Theory of Quantum Gravitation.
The Universal Gravitation Equation defines the force of attraction between two objects in ordinary situations. The equation can be simplified to give the gravity equation for objects near Earth.
Questions you may have include:
- What are the properties of gravitation?
- What are theories of gravitation?
- What is the gravitation equation?
This lesson will answer those questions. There is a mini-quiz near the end of the lesson.
Useful tools: Metric-English Conversion | Scientific Calculator.
Properties of gravitation
All objects consisting of matter exhibit the property of gravitational attraction and tend to move toward each other. This property is considered universal and exists throughout the Universe.
No shield
As far as we know, there is no way to shield the effect of gravitation. There are theories that there exists "dark matter" that repels standard matter, however dark matter has never been detected.
Center of mass
Between two objects, there is a center of mass of the objects. When the objects move toward each other, the will meet at the center of mass. If one is revolving around the other, as in the case of a moon around a planet, both objects are actually rotating around the center of mass.
Escape velocity
It is possible for an object to be propelled at a sufficient velocity away from another object that it will overcome the gravitational attraction between the two. An example of this is when a rocket escapes the gravitation from the Earth.
Gravity
The expressions gravity and gravitation are often commonly interchanged. However, the correct scientific terminology considers gravity as a special case of gravitation for objects near the Earth.
For gravitation close to other large objects, you should include the name of the object, such as: "gravity of the Moon" or "gravity of the Sun."
For astronomical situations, gravitation is the correct term to use.
Gravitational theories
There have been several theories trying to explain the cause of gravitation.
Law of Universal Gravitation
In 1687, Isaac Newton formulated the Law of Universal Gravitation, which states that all objects are attracted toward other objects, due to a force acting at a distance, called gravitation.
Theory of General Relativity
In 1915, Albert Einstein gave another interpretation of gravitation in his Theory of General Relativity. He stated that gravitation was the result of the curvature of space toward matter and not due to some force.
Verification of the theory was in explaining the unusual orbit of the planet Mercury and measuring the effect of gravitation on deflecting light waves as they pass a star.
Theory of Quantum Gravitation
Recent considerations in Quantum Physics say that gravitation is one of four fundamental forces in nature. The force of each is created by an exchange of special or virtual particles. In the case of gravitation, the particle is called the graviton. This interaction leads to an explanation of gravitation at very small distances.
Gravitation Equation
Just as there are several theories about the cause of gravitation, likewise, there are several equations that define the force.
Universal Gravitation Equation
Newton formulated the Universal Gravitation Equation, which allows the calculation of the force between two objects. The equation is:
F = GMm/R2
where
- F is the force of attraction between two objects in newtons (N)
- G is the universal gravitational constant in N-m2/kg2
- M and m are the masses of the two objects in kilograms (kg)
- R is the distance in meters (m) between the objects, as measured from their centers of mass
Gravity equation
The gravity equation is a simplification of the gravitational equation for objects relatively close to the Earth:
F = mg
where
- F is the force pulling objects toward the Earth in newtons (N) or pound-force (lbs)
- m is the mass of the object in kg or pound-mass
- g is the acceleration due to gravity in meters per second squared (m/s2) or feet per second squared (ft/s2)
Other equations
The Theory of General Relativity provides a set of 10 complex equations to describe gravitation. Likewise, Quantum Mechanics and other newer theories explain gravitational force with sophisticated equations.
They are beyond the scope of our material.
Summary
Gravitation is the attraction between objects because of their mass. Other properties of gravitation include attraction to the center or mass, escape velocity and gravity. Theories of gravitation are the Law of Universal Gravitation, the Theory of General Relativity and the Theory of Quantum Gravity.
The Universal Gravitation Equation defines the force of attraction between two objects in ordinary situations. The equation can be simplified to give the gravity equation for objects near Earth.
See the Side Menu for more Gravitation and Gravity topics
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Resources
The following resources provide information on this subject:
Websites
Acceleration due to Gravity Calculations - from Western Washington University
Gravity and Gravitation Resources
Books
Top-rated
books on Simple Gravity Science
Top-rated
books on Advanced Gravity Physics
Mini-quiz to check your understanding
If you got all three correct, you are on your way to becoming a Champion in Physics. If you had problems, you had better look over the material again.
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Overview of Gravitation