Satellite orbital speed homework

[mat331760298]

1. A satellite has an orbital speed of 4.2 x 10^3 m/s. What is its altitude above Earth's surface?
mass of earth= 5.98x10^24kg
radius of Earth = 6.38x10^6m

2. acceleration and force are both centripetal
a=(v^2)/r
F=ma
possibly v^2=(Gmg)/r

3. Need help with algebra
h= distance from Earth surface to satellite
I got h= [(4.2x10^3)^2/a] - 6.38x10^6

 

[CaptainEvil]

Use the fact that to remain in a circular orbit, the gravitational force must equal the centripetal force.

You do not need to know acceleration of the satelite