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Q & A: Earth’s gravity

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Most recent answer: 10/22/2007
Q:
Hi! i was doing an assignmnet and was wondering, how far is it before earth’s gravitational pull is nothing (eg: you wouldnt be pulled towards earth)
- Luis Zacher (age 14)
Albury High School, Albury, NSW, Australia
A:
The strength of the Earth's field falls off inversely with the square of the distance from the center of the Earth. If you were ten times as far away from the center, you'd still be in 1/100 of the field. To the best of our knowledge, that pattern works no matter how far out you go. If it turns out that the universe is finite, then I guess it would have to break down on distances comparable to the size of the universe, because on that distance scale the direction toward the Earth wouldn't be well defined. That distance would probably be at least many tens of billions of light years.

Mike W.

(published on 10/22/2007)

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