Note the Physics

• Instantaneous velocity is a property of the object at a single time; the average velocity of the object depends on two times.
• At any point, the slope of the position vs. time curve is the instantaneous velocity.
• The velocity at two different times may have opposite signs, indicating that the object changed directions.
• When the acceleration is constant, as it is here, the average velocity between two points lies between the instantaneous velocities at each of the points.