Universal Law of Gravity

Universal Law of Gravity - G = 6.672 × 10-11 m 3 /(kg sec...

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Universal Law of Gravity Using Kepler's third law and his own second law, Newton found that the amount of the attractive force, called gravity, between a planet and Sun a distance d apart is Force = k p × (planet mass) / (d) 2 , where k p is a number that is the same for all the planets. In the same way he found that the amount of the gravity between the Sun and a planet is Force = k s × (Sun mass) / (d) 2 . Using his third law of motion, Newton reasoned that these forces must be the same (but acting in the opposite directions). He derived his Law of Gravity : the force of gravity = G × (mass #1) × (mass #2) / (distance between them) 2 and this force is directed toward each object, so it is always attractive. The term G is a universal constant of nature. If you use the units of kilograms (kg) for mass and meters (m) for distance,
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Unformatted text preview: G = 6.672 × 10-11 m 3 /(kg sec 2 ). If you need a refresher on exponents, square & cube roots, and scientific notation, then please study the math review appendix. Spherically symmetric objects (eg., planets, stars, moons, etc.) behave as if all of their mass is concentrated at their centers. So when you use Newton's Law of Gravity, you measure the distance between the centers of the objects. In a bold, revolutionary step, Newton stated that his gravity law worked for any two objects with mass---it applies for any motions on the Earth, as well as, any motions in space. He unified celestial and terrestrial physics and completed the process started by Copernicus of removing the Earth from a unique position or situation in the universe. His law of gravity also explained Kepler's 1st and 2nd laws....
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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