Hey Power, I read physics at university/college so hopefully i can help. You asked...'is g=GM/r^2 the same as F=G(m1*m2/r^2)?\' They are similar, and this can trip people up but they are different in a subtle way. g in this case is the acceleration the object is experiencing and F is the Force. They are related by the equation F=ma which it looks like you have already come in contact with. So you can see that instead you could write a=GM/r^2 instead. Essentially we calling the acceleration towards the Earth g. I hope that helps, if i have the wrong end of the stick and it\'s something else that you are unsure about let me know, i\'d be glad to help. RevJB
