Hello, people of the physics forums. I'm trying to get a grasp on physics, and I have come to my first real roadblock. I'm looking at Classical Mechanics, and more specifically, net displacement. On http://farside.ph.utexas.edu/teaching/301/lectures/node20.html, I have attempted a set of questions, which are answered. I have completed the first two, and do not understand the final one. I don't know what a v-t curve is, and how to find net displacement of this, although I have been searching online for a good week now. I have attempted to get the areas for the various shapes within the graph, but to no avail. Any help would be appreciated.