Distance of a satellite from the earths surface.

[pwphysics101]

1. A television satellite is in circular orbit about the Earth, with a sidereal period of exactly 24h. What is the distance from the Earths surface?



2. I think I have to use Kepler's Laws. Confused as to how to do it without the mass of each. I guess I could find out the mass of the Earth but then..? Can anyone point me in the right direction?

 

[aftershock]

1. A television satellite is in circular orbit about the Earth, with a sidereal period of exactly 24h. What is the distance from the Earths surface?



2. I think I have to use Kepler's Laws. Confused as to how to do it without the mass of each. I guess I could find out the mass of the Earth but then..? Can anyone point me in the right direction?

GMm/r² = ω²r

GM/r = ω²

You know G and M (or can look them up)

ω is the angular velocity. If the period is 24 hours then you know 24 hours is the amount of time it takes for the satellite to travel 2∏ radians. You should probably convert that into radians/sec

 

[pwphysics101]

Thanks! :)