Final answer:
When a ball is traveling at a constant velocity, like the 50 m/s described, its acceleration is zero because there's no change in velocity over time.
Step-by-step explanation:
If a ball has been traveling at a constant velocity of 50 m/s for over 2 minutes, its acceleration must be zero. Acceleration is defined as the rate at which an object changes its velocity. Therefore, if the velocity does not change, the acceleration is zero. This can be understood by looking at a velocity vs. time graph, where a constant velocity corresponds to a horizontal line, indicating that the gradient and hence the acceleration is zero.