Hibisca, who was in my Walton High School APSI last June, writes:
1. When do you teach relative motion, if you do at all? I could not find any direct references to it in the course description, but there is a multiple choice question in the 2014 practice exam (#35) about frames of reference. I also did not find any direct references to it in your "info to memorize" sheets or other materials.
I don't formally teach it at all... usually a discussion comes up at some point, though. That #35 is the one about two balls colliding in a moving train car. I think of it more as a center of mass question -- the center of mass of the two balls keeps going at constant velocity, whether we're observing inside or outside the train car. (See, I'm phrasing it so "relative motion" doesn't come into play -- just the terminology causes headaches with students, so I try to get the concept without the terminology.)
2. How do you handle students who give answers/explanations with calculus? I can't imagine that would be a common issue on the AP exam, since there aren't any calculations, but I did have an issue on their last quiz where I asked students to determine the final position of an object based on a v-t graph. All of the students except for one used the formula for a triangle; one student set up an integral instead. Do you emphasize the need to approach everything algebraically, or do you give full credit to students who correctly use calculus?
They get full credit, as long as the calculus is clearly communicated. As you say, the AP question would be "explain how you could determine", and if the student says, "we need to know how far the ball went from its initial position, that's the integral of the velocity function with limits 2 s and 5 s, that works out to 10 m, so add that to the initial position of 1 m to get 11 m final position" that's beautiful.
If you're worried that such a student might not truly understand what he or she is doing, or if the student uses calculus without words and gets huffy when you don't count it right... then the next quiz question might be "explain how to determine the final position of the object" rather than "determine the final position of the object."
Not that you shouldn't have asked them to "determine the final position of the object." I start there, too. But then after I'm comfortable that everyone can do the calculation, I insist on the AP Physics 1-level explanation.
More questions about your physics classes? Send 'em via email, and I may publish as a Mail Time.