I've been trying to figure out different ways to explain to my students how to figure out the time in the air for a projectile and ran into the following issue:
When a projectile is thrown with an initial vertical velocity component and comes back down to the same height, the equation for average velocity (displacement / time = (vf+v0)/2) cannot be used. The equation is useful when the vertical displacement is nonzero, however.
Thus, I've been trying to figure out a clear, conceptual way to explain why this equation won't yield an answer for this specific scenario and am struggling. Can anyone help me out? Thank you!
Note that while I understand you can figure out the time to the max height and then double that time to get the answer, that avoids the issue that I'm trying to be able to explain.