Homework Help: Satellite in Orbit?

1. Sep 24, 2006

wolly6973

A spy satellite is in circular orbit around Earth. It makes one revolution in 6.04 hours.
(a) How high above Earth's surface is the satellite?
(b) What is the satellite's acceleration?

I really have no idea what to do on this. All of the equations that I have, I cannot solve because I don't have enough info. Anything that anyone can do to get me started would be greatly appreciated.

2. Sep 24, 2006

skeeter

satellite's centripetal force = gravitational force
mv^2/R = GMm/R^2
v^2 = GM/R
R = GM/v^2
also ...
v = 2pi*R/T

you now have all the necessary data and equations to solve for R.

remember that R is the distance between the satellite's and earth's respective center of masses, T is the orbital period in seconds, G is the universal gravitation constant, and M is the mass of the earth.

3. Sep 24, 2006

wolly6973

So I get the equation narrowed down to R^3=(T^2*G*M)/(2pi^2). But I can't seem to get it to work out to the correct answer? Did i mess something up?

4. Sep 24, 2006

Dorje

For one, the '2' with the 2pi is squared along with the pi (as its written above, it looks like only the pi is squared), so the demoninator should be 4pi^2. The period T should be converted from 6.04 hours to seconds, and to get R, the cube root of the right hand side of the equation must be computed.