Open this video of a boy sliding e across the ice. The screen shows a data table, a position against time graph, and a velocity against time graph. The symbols used are t for time, x for position, Vx for velocity, and ay for acceleration. Click the play button, and watch the video. Then study the position against time graph. What is the change in the motion of the boy? How do you know? Is the acceleration of the boy positive or negative?