<p>You shouldn’t be using E=pc to find the momentum of the electron, because that is usually used for photons. I remember multiple AP problems having the same scenario where using E=pc would give you the wrong answer; you need to find the electron’s velocity and then do p=mv.</p>
<p>Oh thanks! I was doubting myself after several of my friends told me they used E=pc.</p>
<p>yeah, you have to solve for v.
Btw, any one has any ideas of the curve this year?</p>
<p>How did you all prepare for this exam?</p>
<p>I am just going through all the released frqs.</p>
<p>I am taking the late exam…oh, I am so nervous!</p>
<p>Practicing FRQ helped a lot. You could practice MC as well, but that revolves around concepts mostly. For me, I just took tests after tests after tests until I knew what I had to state and show to receive full points in the FRQs.</p>
<p>Oh ok, thanks! That is what I have been doing. I have 3 years left to do. It is so hard to find multiple choice, though!</p>
<p>Anyone can confirm how to do 5(c)ii and 7 (c)?</p>
<p>Right after this AP test I felt horrible, we all did. While the multiple choice was easier than expected, the FR seemed way more difficult. </p>
<p>Throughout the year our tests had previous FR questions and they all seemed a lot easier than this year’s (I got 100s on all those tests, except for 3 at the most). I remember that when I first opened the test and looked at the first problem I scratched my head, wrote a few things to see if I could solve, and then moved on after 2 mins. I eventually came back and had my Ah Hah moment (only horizontal velocity, so y=0.5gt^2, then I could solve the rest of the problem).</p>
<p>But, my teacher did the problems and showed us the solutions and I did surprisingly well. The only troublespots that stuck out were that I got the last 2 or 3 parts of the flux ? wrong (I hate flux, I almost started to write about flux capacitors and Back to the Future, a prose that would have ultimately ended on the space-time fabric, distortion of time and space by mass, and the ability of blackholes to create such distortions) and the thickness of film, which I simply did not know how to do. On the +, I got stopping potential right even though I had not seen that terminology before (yay conservation of energy, KE=UE=qV).</p>
<p>I got my SAT Subject score back and got a 760 (A nice surprise, that test felt like a beast too), so I have good prospects for the AP test. My teacher has excessively high expectations, expecting me to get a 5 OR ELSE (his joke). I’d be happy if I pass, in college I’ll have to take calc-Physics anyway, so this credit is useless.</p>
<p>For best swimmer:
5c) My teacher said that when light goes into the film, it refracts and then reflects of the back of the film. You want all the light to create destructive interference it makes no sense to me (mathematically, at least) 
I left it blank</p>
<p>7c) This is conservation of energy (my lucky guess) you set:
kinetic energy = electric potential energy = qV, solve for V (q of electron is from constant sheet)</p>
<p>5c) It’s quite a convoluted equation that’s not given on the equation sheet. I don’t feel like giving a giant explanation, but I think that if you go to AP Central, you can find a thin-film interference FRQ from the past and look at the answer for an explanation of how to do that type of question.</p>
<p>7c) An easier way to do stopping potential is to take KEmax in eV and put that number in volts. Why that is? I have no idea, that’s just how it works.</p>
<p>314159265,</p>
<p>Your method works because the unit eV is the charge of 1 electron multiplied by 1 Volt (U_E=qV=eV). It works in this case because we are specifically dealing with the emission of a single electron. The reality is by converting to eV, you did the same thing I did (dividing by the charge of an electron).</p>
<p>I see. That makes sense now! Thanks!</p>
<p>I GOT A 5
for anyone that reads this for next yr
all i did was use my school textbook
dont waste money on PR like i did</p>