We have looked at potential wells, which are just graphs of potential energy as a function of position. The classic way of thinking about this is to imagine one object fixed at the origin, and have a second object moving along the x-axis. The graph tells us the potential energy between the two as you move that second object. We look at the potential energy gradient in order to determine the force function, F = -dU/dr, or in other words the force graph is found by plotting the negative slope of the potential energy graph. I outline this by using the 'Nike' problem from an old AP exam. Check it out!