How Do You Calculate the Height and Speed of a Geosynchronous Satellite?

[mortho]

Homework Statement

A geosynchronous satellite is used for communication and stays at the same place above the equator all the time. Calculate the a)Height of the satellite
b)Speed at which it travels.

Homework Equations

v=2πr\t
a=v2/r
F=Gm1m2\r2

The Attempt at a Solution

I'm not sure how to start this,but i started with velocity but didn't know what radius to use. Is it double the radius of the earth?

 

[hotcommodity]

I can't stay long but here's a hint: You're solving for the radius "r". What is the period of the Earth's rotation, in other words, how long does it take for the Earth to make one complete revolution? You know by application of Newton's 2nd law that the gravitational force will equal ma, as it is the net force acting on the satellite. After finding "r", make sure you subtract the radius of the Earth to get the height above the Earth at which the satellite orbits.