I was walking through "downtown" Golden, Colorado this afternoon and when it came time for dinner, I stopped by a Quizno's along the street to pick up a sandwich. They had patio seating, and since the weather was so nice I thought I'd enjoy my sandwich and American-style sugar-free iced-tea outside. Not too long into my sandwich, I couldn't help but overhear the conversation of two young girls sitting behind me. The term, "free-body diagram" caught my attention, and sure enough, it sounded like they were working on some sort of physics problems. At first I thought maybe they were university undergrads studying statics or dynamics or something related, but once I heard them mention "air resistance" I figured they were probably just high-school students. The problem they were working on sounded like a hypothetical, "if you were standing on a scale and accelerating upwards, why would the scale read more?" Their explanation was heavily based on air resistance. Something like, "oh you know, because there is an equal and opposite reaction for everything, the air resistance pushing down on you would increase the reading on the scale."

I remember that type of explanation. For some reason, high-school physics students have some mass obsession with using air resistance as an explanation for so many types of physics problems.

I mean technically, their answer was not wrong, but it's not the most correct answer. Sure the air resistance was adding some additional force, but it's probably a better answer to refer to something like inertia, and then mention something about how the scale doesn't measure "weight" in terms of mass, but rather as a force. Then you would bring in F=ma to demonstrate that. Use your free-body diagram to show all the accelerations and forces, which should result in the numbers falling out somehow to show that the scale reads a higher weight. Then if you feel so inclined to, you can mention air resistance as an additional, but possibly negligible force depending on the size or geometry of the object (i.e. the drag coefficient).

I was almost tempted to just turn and say, "excuse me, I couldn't help but over hear your conversation about air resistance..."

But I'm pretty sure I've mentioned "air resistance" at least a few times in high-school physics before.