Here is the problem you were working on in class.
I suggest you DO NOT look at the solution. Work as hard as you can. If you are still stuck, ask questions in class.
Here is a bonus post.
This is for you
I usually give a short lecture in class about this topic, but since we already touched on it – here is a link. Read if you like.
I wrote this for you.
Here is a post about one of xkcd (the comic) post.
Here is a post you might like. It is an analysis of some gravitational wells.
Yes, I know. We haven’t looked at potential energy yet. However, this does show how near the surface of the Earth the gravitational force is essentially constant. Sorry, I thought I had a post that did the same thing with forces, but I was wrong.