Question about satellite motion?

[Tangeton]

This is one of the questions in the book without an answer and it is really frustrating that I can't check if my through process is correct.

Two satellites X and Y are seen from the ground crossing the night sky at the same time. Satellite X crosses the sky faster than Y. State with a reason which satellite is higher.

I wrote: Satellite Y as the gravitational attraction doesn't act as much on it so it moves around the Earth slower than X does.

Is my answer correct?

 

[haruspex]

Half right. Can you write down an equation for the force and resulting acceleration of a satellite at radius R?

 

[Tangeton]

Half right. Can you write down an equation for the force and resulting acceleration of a satellite at radius R?

a= v^2/r and F = mv^2/r , where r is the distance from centre of the Earth to the satellite. Where do I go from here?

 

[haruspex]

F = mv^2/r , where r is the distance from centre of the Earth to the satellite.

Since it is in orbit, what else is F equal to?