Consider the time vs. position plots of an object in the graph below:
Q: During which interval is the object moving forward with a constant velocity? Over which interval is the object accelerating, sitting still, and moving opposite to the initial direction of motion?
A: We begin by designating the vertical direction as being the forward direction. During the AB interval, the position of the object disproportionately increases as time transpires. Thus, the object in question accelerates over the AB interval. The slope of the line over the BC interval is steady; this represents an object moving forward at a constant velocity. The object is sitting still over the CD interval, and it is moving in the reverse direction over the DE interval. The slope of the line from D to E is steeper than the one from B to C, so the object moves in the reverse direction at a higher velocity than it did moving forward.
RENAISSANCE PHYSICS 