This physics video tutorial explains how to find the acceleration from a velocity-time graph. The acceleration is positive whenever the velocity is increasing and it's negative whenever the velocity is decreasing. The acceleration is zero whenever the velocity is constant. The acceleration is equal to the slope of a velocity-time graph.
Motion Time Graphs:
https://www.youtube.com/watch?v=nUb7xfkc0Ac
More Physics Videos:
https://www.video-tutor.net/physics-basic-introduction.html
