Lucretius said:
You got Form B of the free-response questions, from your description. I didn't have any sort of table for section 1. Was
this the test you had?
Here is the test I took. I didn't think the multiple choice was very hard; the practice multiple choice exams I had taken in class were much more difficult than this years'.
Look at question 3 on my free response section and see if you can tell what they wanted there. I left that whole page blank.
Yup, turns out I did have form B..
On the subject of tests on the website, they released the AP Physics C Mechanics test!
I mean... err... I have the test this Friday, and according to records there has never been an AP Physics C form B. I hope I get lucky. :D
So question 3 from your paper...
Since it says the net electric field at point P is zero, The electric field produced by q1 plus the electric field produced by q2 = 0... so, from there, you can plug in your known values and solve for q2.
Chances are, however, q2 is positive because since q1 is negative, a test charge 1C at point P would be attracted to it, (to the right), so it needs a positive charge, q2, to repel it to the left enough to keep the net electric field 0 at that point I guess.
For part c, the electric force on q2 would be the force on q2 caused by q1, Coulomb's law...
d... Electric potential would be 0 when
q1/4pi*e*d = q2/ 4pi*e*(0.3-d)
And solving for d.. (d would be the distance from q1 to the point)
e... I would integrate the coulomb force from infinity to the point, but I'm not sure if that's acceptable on physics B. You could say, instead, that it's = to the potential energy. I'm not sure why, though.