# Satellite Orbit Problems

• TjGrinnell

#### TjGrinnell

Homework Statement
I have a satellite with a mass of 30.0 kg that I wish to put into a circular orbit 450,000 m above the surface of the earth.
15. How much will the potential energy of the satellite – earth system increase by?
16. What must the kinetic energy of the satellite be when it is in orbit?
17. What will the magnitude of the gravitational force on the satellite be when it is in orbit?
18. What will the period of the satellite's orbit be? If the orbit is above the earth's equator, how long will it take for me to see the satellite again in the same spot in the sky?
Relevant Equations
U(g)=-(GM(p)m(s))/r^2
I just have a question on the problem itself. If I am putting the satellite into orbit 450,000 m above the surface, then would r=6,371,000 m(earth's radius)+450,000 m? And what mass of Earth should I be using, in kg of course.

TjGrinnell said:
I just have a question on the problem itself. If I am putting the satellite into orbit 450,000 m above the surface, then would r=6,371,000 m(earth's radius)+450,000 m?
Yes.
TjGrinnell said:
And what mass of Earth should I be using, in kg of course.
Look it up on the web, I have not memorized it.