# Homework Help: Satellite in circular orbit

1. Sep 30, 2007

### BuBbLeS01

1. The problem statement, all variables and given/known data
A satellite is in a circular orbit around the earth. The period of the satellite is 22.0 hr. Calculate the radius of the orbit of the satellite. Data: Mass of the earth = 5.98·1024 kg.

2. Relevant equations
I thought I could use...
T^2 = (4pi^2/GM) * r^3
but I am not getting the right answer, can someone give me a start on this?

2. Sep 30, 2007

### ColdFusion85

This is the correct formula. Did you convert the period from hours to seconds? If not, you are going to get the incorrect answer. You have to make sure everything is in SI units.

3. Sep 30, 2007

### ColdFusion85

I also assume you mean the mass of the earth = 5.98*10^24 kg.

4. Oct 1, 2007

### BuBbLeS01

yes I converted it to seconds and got 1.84x10^8 m, but its wrong.

5. Oct 1, 2007

### D H

Staff Emeritus
Show your work. You made a mistake somewhere, as you should have about 40000 km had you applied the equation properly.