Official AP Physics C Thread 2012

Test Preparation AP Sciences
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<p>Let’s all hope for E&M 1 to be a nice Gauss’s law question at least! :p</p>

<p>(as long as they don’t do a painful density is a function of the radius and you have to integrate rho dV to get the whole charge like they did one year…)</p>

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<p>How are the FRQs usually set up? I notice there is usually 1 gauss’s law and electric field question and 1 circuit question but what about the third one?</p>

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<p>Does anyone know where to get the 2009 mc questions online for e and m or mechanics</p>

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<p>Any predictions on what the FRQ’s will be?</p>

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<p>Heh I was reading this thread and noticed someone posted the links to my teacher’s review pdfs on here (the rosephysics links). He’ll definitely be happy to see that! :P</p>

<p>I’m kinda nervous about tomorrow. I’m really really bad at the multiple choice, but sometimes I can score really high on the frq’s. It’s basically gonna come down to what frqs they give, because if they throw some curve ball ones (Mechanics 2009 #2 lol) a couple points doesn’t really compensate for a question like that where 81% of the kids got a 3 or lower.</p>

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<p>This sums it up for me: [Futurama</a> Fry - not sure if i know everything or i am just delusional](<a href=“quickmeme: the funniest page on the internet”>Not sure if I know everything, Or I am just delusional. - Futurama Fry - quickmeme).</p>

<p>I have been reading through the whole textbook and I feel solid on every topic…</p>

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<p>Remember you need Green’s theorem to evaluate Electric and Magnetic Flux, Ampere’s law, and Faraday’s law of induction. I believe those are the only ones you will need Green’s theorem for the test.</p>

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<p>I’m so bad at all of the conceptual stuff. Lenz’s law, kepler’s laws, etc. Whenever I see something involving vectors (direction of induced current or emf, for example), I just forget. Always have it backwards.</p>

<p>Edit: Green’s theorem? I just memorize the laws, they’re very basic… unless you mean prove them?</p>

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<p>Remember the right hand rule and you are golden conceptually. Also remember that the force acts on the positive charge; negative charge will have the opposite force.</p>

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<p>Yeah, I still have issues with motional emf though. I mean it’s easy to calculate but I can never think of the direction. Always opposes what caused it, or something?</p>

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<p>Again, right hand rule. Think about it. Referencing to this picture: <a href=“http://img.sparknotes.com/content/testprep/bookimgs/sat2/physics/0003/barmoving.gif[/url]”>http://img.sparknotes.com/content/testprep/bookimgs/sat2/physics/0003/barmoving.gif&lt;/a&gt;. As the bar moves toward the right, there is a force on the positive particles toward the top of the page. Remember that current is always opposite the electron movement. Then you do right hand rule again on that current, which is going to the top of the page. That magnetic field now has a force toward the left of the page on the particles in the bar. So it has a “restorative” force that opposes the bar movement. That’s it. Sorry for the not so accurate vocabulary.</p>

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<p>how do you guys feel about the practice tests on the 2012 princeton review. I am only doing the mechanics parts because i’m only taking the mechanics test. I feel that the first practice test is harder than the second one. the first one also seems more calculus oriented</p>

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<p>^^ Ok, makes more sense now.</p>

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<p>@davidthefat – when the bar moves right which makes the current in the bar move upward, isn’t there an induced magnetic field pointing out of the page on the left side of the bar and into the page on the right side? Does that have any effect on the resisting force to the left? A B field out of the page on the left should create a force to the left, but the B field to the right of the bar points into the page which should create a force rightward.</p>

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<p>It shouldn’t, the left side points out of the page; the current on the left side of the loop is going toward the bottom of the page. That induced magnetic field has a force going to the left side of the page. But what’s that force acting on? The stationary loop. Like trying to lift yourself up by pulling on your feet, the system does not move. There is nothing to “push” on the right side of the bar, so you can disregard the induced magnetic field on the right. So technically, no effect.</p>

<p>edit: crap… The left side of the loop induces a magnetic field itself…</p>

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<p>OK, thanks, I’m just overthinking it.</p>

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<p>I took AP Physics Mechanics today (International version).
I did not do really well but since the curve is usually generous, i think i may get a 5</p>

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<p>I should have known that if the multiple choice was going to be that easy (relative to other years), then the FR would be hell.</p>

<p>We aren’t supposed to discuss questions, of course, but… why would ETS do that to us? I’m really hoping for a generous curve, because that was borderline unfair.</p>

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<p>I feel you. FR was a lot more brutal than I was expecting. :/</p>

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<p>Anyone else wasn’t able to finish all the FRQ’s? I was midway through the second one when the 10 minute mark was called. ■■■</p>