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Gravity is not caused by the rotation of the earth,
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Nobody ever said it was caused by the rotation of the earth.
Read again what I wrote in my previous post.
Correct.
And the distance from the masses center determines the centripetal or center seeking force required to keep you in the same spinning frame of reference.
That is why you and your airplane lose weight when you gain altitude!! The farther from the center, the less center seeking force required.
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GRAVITY was explained by Isaac Newton with a formula that says two masses M1 and M2 are attracted to each other by a Gravitational Force. The Gravitational Force, F1, is calculated by the equation below:
F1 = G x M1/R x M2 / R
Where R is the distance between the center of M1 and the center of M2 and G is the Constant of Gravitation.
If you use metric units, M! and M2 are kilograms, R is meters, G is
6.673 / 100000000000 Newton-Meters per kilogram per kilogram, and
F1 is Newtons.
CENTRIPETAL FORCE, F2, is the force that pulls on a string if you tie a rock on the end of a string and twirl the string with the rock on the end around your body. The Centripetal Force is the force that pulls on the string. A similar thing happens when a planet orbits around the sun or when our moon orbits around the Earth or when the space shuttle orbits around the Earth. The smaller object revolve around the bigger objects. The string is like gravity.
F2 = M! x V x V / R
Where V is the velocity (speed) of the rock or satellite
If you use metric units, V is meters per second
ORBITS: A less massive object M1 can orbit around a more massive object M2 if the Centripetal Force of the orbiting object is the same as the Gravitational Force between the two object. If you look at F1 and F2 above, then there is an orbit if F1 = F2. Another form of this equation is
G x M1/R x M2 / R = M1 x V x V / R
Or the speed of the satellite, M1, must be V = SQRT (G x M2 / R)
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http://library.thinkquest.org/3806/ORBMECH.HTM