# Ocr physics text book question on gravitational field

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Thread starter 6 years ago
#1
How far above the surface of the earth is the gravitational field strength a)half b)1/4 of it's value at the surface? The radius of the earth is 6.4 x10^6 HELP PLEASE
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6 years ago
#2
(Original post by unique_freak)
How far above the surface of the earth is the gravitational field strength a)half b)1/4 of it's value at the surface? The radius of the earth is 6.4 x10^6 HELP PLEASE
You are interested in the distance from the Earth's center of gravity, for points on and above the surface, the field strength obeys the well known inverse square relationship.
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6 years ago
#3
G IS PROP 1/r^2

g = k/r^2

You know surface g value and radius.

Find k.

Then you'll know which g values you want, and solve for r. Then subtract earth's radius cos you want height above earth
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Thread starter 6 years ago
#4
(Original post by L'Evil Fish)
G IS PROP 1/r^2

g = k/r^2

You know surface g value and radius.

Find k.

Then you'll know which g values you want, and solve for r. Then subtract earth's radius cos you want height above earth
Thank uuuuuuuu!
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