Final answer:
The object's velocity can be described as constant if the velocity-time graph is a horizontal line. If the position decreases in the positive direction, the velocity is negative, and if the position increases, the velocity is positive. A horizontal acceleration-time graph indicates constant acceleration, affecting if the velocity is increasing or decreasing.
Step-by-step explanation:
Based on the given descriptions and figures relating to velocity and position with respect to time, we can deduce the characteristics of the object's velocity. If an object is represented by a graph where it is continually decreasing its position in the positive direction, negative velocity is depicted. However, if the velocity vs. time graph is a horizontal line, this indicates that the object is now traveling at constant velocity. In the context where the object is continually increasing its position in the positive direction, the object's velocity is considered positive.
If the acceleration vs. time graph is a horizontal line at some value, it indicates that the acceleration is constant, which means the velocity is either increasing or decreasing at a steady rate, depending on whether the line is above or below the horizontal axis (positive or negative acceleration, respectively).