Question

(27%) Problem 1: One of the challenging ideas of using energy at the atomic and the molecular level is the idea of bound states. What this means is that you might start with two objects that have essentially zero kinetic energy, they get close and interact strongly in an attractive way. They find some way to emit energy into another form and wind up being stuck together -- bound. You have to put energy in -- do work on them -- in order to get them apart. Let's work through the language of potential energy to see how to talk about this. (Since we are making a model that looks like atoms and molecules, we will ignore friction.) 30 20 10 Let's first talk about a simple problem that you have now had some practice with looks like a dip in the ground as shown in the figure. A potential shape like this is often referred to as a potential well, since it looks like a dug-out area for a well the motion of a skateboarder on a track. Suppose the track 1 1 2 3 4 10 20 40
(zoomed in of the graphs)

please help with C, included B for reference

Answer 1

The PE is really only relative. We can decide where we take it to be 0. If we choose it to be 0 when she is outside the well and at rest (a convenient place), then if her total energy is positive she can leave the well with a positive speed. If her total energy is negative it means that positive energy has to be added to bring her to a point at rest outside the well (to the value of 0 energy).