The figure below shows four different motion diagrams. The green arrows represent the velocity vectors. For which of the diagrams can you say that the magnitude of the acceleration is clearly changing as a function of time?
ANSWER: For none of the diagrams. All diagrams are consistent with an acceleration that has a constant magnitude.
The acceleration can be solved by subtracting two consecutive velocity vectors. If you do that for all the diagrams, the magnitude of the acceleration is consistent for all.