# Potential Energy Gravitational

1. Oct 14, 2008

### Husker70

1. The problem statement, all variables and given/known data
A satellite of the Earth has a mass of 100kg and is at an altitude of 2.00x10^6m.
(a) What is the potential energy of the satellite-Earth system? (b) What is the magnitude
of the gravitational force exerted by the earth on the satellite? (c) What force does the
satellite exert on the Earth?

2. Relevant equations
(a) Ug = - G m1m2/r
Mass of Earth = 5.98x10^24 kg
Radius of Earth = 6.37x10^6 m

3. The attempt at a solution
(a) I took the mass of the earth times the 100kg satellite/the Altitude plus the radius of earth
Ug = G (5.98x10^24kg)(100kg)/2.00x10^6m(6.37x10^6m)
I'm not sure what the G is for.
Thanks,
Kevin
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Oct 14, 2008

### G01

G is the universal gravitational constant:

$$G=6.67*10^{-11}\frac{Nm^2}{kg^2}$$

3. Oct 14, 2008

### Husker70

Got it thanks. Not sure why I couldn't find that but I got the correct answer.
Not sure what equation to use for part b
Thanks,
Kevin

4. Oct 14, 2008

### G01

For part b), you want Newton's equation for the force of gravity between two objects:

HINT: The equation your looking for should also contain a big G.

5. Oct 14, 2008

### Husker70

I think I got it using this equation.
Thanks,
Kevin

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