Homework Help: Ive got a gravitational Potential Energy Question

1. May 11, 2010

clearlyjunk

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

1. The problem statement, all variables and given/known data
http://img190.imageshack.us/i/backofgravitationalpote.jpg/
Qeustions at that pg

1.Examine teh graph

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

2. Relevant equations

2.What the fudge is going on with the eg1 and eg2

3. The attempt at a solution

My friend did the solution and passed a copy of his sheet to me. I dont understand why stuff is happening.

2. May 11, 2010

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.

Last edited: May 11, 2010