Answer
(a) The object has the highest speed from D to E.
(b) At point D, the object reverses from a positive direction to a negative direction.
At point E, the object reverses from a negative direction to a positive direction.
(c) From $t=0$ to $t = 3~s$, the object moves 20 meters.
Work Step by Step
(a) The slope of the position versus time graph is the velocity. The section with the steepest slope has the highest speed. Since the steepest slope is the section from D to E, the object has the highest speed from D to E.
(b) At point D, the object reverses from a positive direction to a negative direction.
At point E, the object reverses from a negative direction to a positive direction.
(c) At $t = 0$, the object is at position 0.
At $t = 3~s$, the object is at position 20 m.
From $t=0$ to $t = 3~s$, the object moves 20 meters.
