Ive got a gravitational Potential Energy Question

[clearlyjunk]

HEre is the page! http://img190.imageshack.us/i/backofgravitationalpote.jpg/

Homework Statement

http://img190.imageshack.us/i/backofgravitationalpote.jpg/
Qeustions at that pg


1.Examine the graph

2.Calculate the change in potential of a 25 kg mass which is placed into orbit 520 km above the surface of the earth.

Homework Equations

1.Please explain the graph!
2.What the fudge is going on with the eg1 and eg2

The Attempt at a Solution

My friend did the solution and passed a copy of his sheet to me. I don't understand why stuff is happening.

 

[zachzach]

The formula for gravitational potential energy is $$U = \frac{-GMm}{r}$$. The graph is just U vs. r so $$U = \frac{-A}{r}$$ where A = GMm and r goes from 0 to infinity (the smallest physical value of r is 0). Also, in the graph r₁ should correspond to E₁ and r₂ should correspond to E₂ so the graph is labeled wrong.