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 * Universal** **Gravitation**


 * Newton's Law of Universal Gravitation ||
 * Gravity and Distance: The Inverse-Square Law ||
 * Universal Gravitatoin ||

 **Newton's Law of Universal Gravitation ** Every object attracts every other object with a force that is directly proportional to the mass of each object. Mass and distance are the two determining factors for gravity. The greater the mass, the greater the force of attraction between two objects. Also, the force decreases as the square of the distance between the centers of the mass of the objects increases. F = m1 m2 / d² The universal gravitational constant is expressed with //G//. F = G m1m2 / d²

Isaac Newton was sitting underneath an apple tree, as legend goes, and was inspired to create his concept of gravity. He understood gravity, as discovered by Galileo, and theorized that all objects continue to move at a consistant speed in a straight line.
 * The Falling Apple**

Newton soon came to the conclusion that the moon must be following around the earth, rather than following down the earth. He said that falling beneath the straight line would follow if no force acted on a projectile circling the earth.The moon has velocity that is paralell to the earth. It will continue to fall around the earth as long as there is no resistance to slow it's speed. Newton tested this theory by finding that mass has no effect on freely falling objects.
 * The Falling Moon**

The moon has velocity paralell to the earth. It will continue "falling" around the earth as long as there is no resistance to reduce it's speed.
 * The Falling Earth**

The greater the distance from the earth's center, the less an object will weigh. The influence of gravity varies as the inverse square of the distance of ceach object from its source.
 * Gravity and Distance: The Inverse-Square Law**

=Newton's law of universal gravitation states that every object attracts every other object with a force that for any two objects is directly proportional to the mass of each object. The force also decreases as the square of distance between the centers of masses. This law can be expressed as: = 10-11 N m2 / kg2
 * Newtons Law of Universal Gravitation **

Universal gravitation explains why the earth is round. The earth is round because of gravity, any corners of the earth have been pulled in so the earth is a giant sphere. All the planets have a gravitational effect on each other. The sun has the stongest influence, but there is still a slight, but noticable pull from the planets. For example, Saturn is near Jupiter so its pull disturbs Jupiters path, causing a perturbation. Perturbation is when planets dviate from their normal orbits. Gravitation extends beyond the solar system. The rotation of binary star systems are dictated by gravity as well as the shape of galaxies. The fate of the universe is also dictated by gravity. The universe is 10 to 15 billion years old and was created in the Big Bang. The universe is either expanding or oscillating.
 * Universal Gravitation**