This is due

select a graph for the situation. you leave home and head to a meeting you start out at a fairly steady pace until you get to pace until you get to a crosswalk. while stopped at the crosswalk you realize that you have forgotten your notes. you turn around and head back home at the same fairly steady pace. you grab your notes and then run to your meeting without stopping, although along the way your pace slows down a bit. the graphs show the amount of time that has passed and your distance from home