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Earth and Satellites

  • Thread starter DeeNoo
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  • #1
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Homework Statement



A geosynchronous satellite is one that stays above the same point on the equator of the earth.
Determine the height above the Earth's surface such a satellite must orbit and find it's speed.

Homework Equations


Fg = GM1M2/r^2

The Attempt at a Solution



I really don't know where to start, but I thought that maybe I could use the T1^2/R1^3 = T2^2/R2^3 Where T1 = The time period of the moon and T2 = is the time period of the satellite. I don't know if we're suppose to know the distance of the moon to the Earth. Someone please help. My teacher can't teach.
 

Answers and Replies

  • #2
Andrew Mason
Science Advisor
Homework Helper
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Homework Statement



A geosynchronous satellite is one that stays above the same point on the equator of the earth.
Determine the height above the Earth's surface such a satellite must orbit and find it's speed.

Homework Equations


Fg = GM1M2/r^2

The Attempt at a Solution



I really don't know where to start, but I thought that maybe I could use the T1^2/R1^3 = T2^2/R2^3 Where T1 = The time period of the moon and T2 = is the time period of the satellite. I don't know if we're suppose to know the distance of the moon to the Earth. Someone please help. My teacher can't teach.
Follow these four steps:

1. What is the force (gravity) on a satellite of mass m at a distance r from the earth's centre?
2. What is the (centripetal) acceleration of a satellite prescribing a circular orbit of radius r (ie. from the earth's centre)?
3. How are 1 and 2 related?
4. Now, suppose that the angular speed of the satellite is the same as the angular speed of the earth's rotation about its axis and solve for r. Then work out what that is in terms of distance from the surface of the earth.

AM
 

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