1. a) Write down the SI (i.e., the metric system) units of position (x), time (t), velocity (v), and acceleration (a).[1 point each] b) Draw a single position versus time graph (i.e., an x t graph) for an object whose position is negative, whose velocity is negative, and whose acceleration is zero. Label your axes and the origin clearly. (You may draw any graph that meets these requirements.) [4 points]