# Homework Help: Gravitational potential

1. Mar 1, 2008

### Ania

1. The problem statement, all variables and given/known data

i have to determine the potential energy of a satellite around a circular orbit and i have been given

the radius of the circular orbit is 3Re and mass of a satellite of 5.00*10^2 -- ONLY

2. Relevant equations

so can use the Gmm/r...... and subsitute the mass of the circular orbit as 1.

3. The attempt at a solution

2. Mar 1, 2008

### R.Harmon

Not quite sure what you mean by mass of the circular orbit, but if you use $$U=\frac{-GMm}{r}$$, where G is the gravitational constant, M is mass of the earth, m is the mass of the sattelite, and r is the radius of the orbit, you should be able to work out the gravitational potential energy U. You might just need to google the mass of the earth and gravitational constant. Hope this helps.

3. Mar 1, 2008

### Ania

no...the satellite is orbiting around a unknown circular orbit with a radius of 3Re

4. Mar 1, 2008

### tiny-tim

Hi Ania! Welcome to PF!

What do you think is unknown about it?

(Re means earth radius, of course.)