# Gravitation Field Question

1. Dec 4, 2006

### quickslant

I just want to know if there is enough information for me to answer this question.. to me it just seems like i should be given some more information

A satellite is designed to orbit Earth at an altitude above its surface that will place it in a gravitational field with a strength 4.5 N/kg

Calculate the distance above the surface of Earth at which the satellite must orbit.

Given :
Me = 5.98 x 10^24
Radius of earth = 6.38 x10 ^6 km or 6.38 x 10^9 m
radius of satellite (r2) = RofE + X

it just seems like i should have the mass of the satellite to answer this question, can someone tell me if i have enough to solve it?

2. Dec 4, 2006

The gravitational field strength is given by:

$$g = \frac{GM_{E}}{r^{2}}$$

So you have $$4.5 = \frac{G(5.98\times10^{24})}{(R_{E}+X)^{2}}$$ and solve for X.

Last edited: Dec 4, 2006
3. Dec 4, 2006

thank you..

4. Dec 4, 2006

### quickslant

ok.. im working this out and im getting totally confused again
can someone show me how to isolate x in this equation?

5. Dec 5, 2006

### quickslant

Can someone tell me if this is right?
(Radius Earth + X)^2 = G(Mass earth)/ 4.5

or X = (Sqrt (G(Mass earth)/ 4.5)) - Radius Earth??

6. Dec 5, 2006

### Kurdt

Staff Emeritus
looks ok to me

7. Dec 5, 2006

### quickslant

Thank you thank you thank you