Sure-- per a sibling comment of mine, it tricks half of freshmen at Caltech. Throwing it at a random 8th or 9th grader can be expected to be even worse.
> I would. I expect physics students to get past their knee-jerk intuitions and think about the principles they've been taught. Otherwise what's the point of learning physics?
In 8th grade?
A) To learn a little bit about the world works
B) to get a whole lot of practical experience with dimensional analysis, applying formulae, and drawing diagrams of simple systems
C) to begin to decide if deep study on this track might be for you, hopefully building a little bit of wonder that might inspire you to study it more deeply and pay attention to physics in the world around you.
They are freshman, i.e. untrained minds. Me, I probably would have failed that question at the time, too. Such a question wouldn't have been on a test, however, as test questions always involved a lot of math.
I remember one inglorious physics midterm exam that over half of the students flunked. The prof had some angry words for the class.
> In 8th grade?
Sure, if you'd laid the groundwork in class.