# Satellite Orbiting Earth Energy

1. A 962kg satellite orbits the Earth at a constant altitude of 99km. How much energy must be added to the system to move the satellite into a circular orbit with altitude 195km?

2. Homework Equations :

E = (-GMm)/2r
$$\Delta E$$ = Ef - Ei

3. My work (which produced the wrong answer)...

Ei = (-GMEms)/(2(rE + 99000m))

Ef = (-GMEms)/(2r(E + 195000m))

$$\Delta E$$ = ((-GMEms)/2)((1/rf)-(1/ri)

The answer needs to be in MJ. I got 858MJ which is incorrect.

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## Answers and Replies

Delphi51
Homework Helper
Hi blackheart. The method looks good. I got about half your answer.
Did you get 2.26 x 10^-9 for the difference between the 1/r terms?

Oh! I didn't divide by two... I have it now. Thanks a bunch.

Delphi51
Homework Helper
Most welcome.