December 2007 Physics

<p>What was the leaf electroscope one? The plastic cup one? and the half-covered concave lens?</p>

<p>any one find this version a lot harder than PR/Collegeboard tests</p>

<p>I think the plastic cup was 3W after the thickness has been increased....Half covered concave lens?? wasnt it a CONVEX lens??</p>

<p>ya..it was convex...nd yes..this test was much harder than the previous..for heavens sake..put some mechanics..im much better at those thn the other stuf...i hope the curve is low..so i can get 700+ and be a happy bunny :)</p>

<p>Convex lenses: no image</p>

<p>Half covered lens i put no image but im not sure.</p>

<p>I'm pretty sure its a bright spot
This is because rays are falling on the top half of the lens so they do get converged..The reason why an image is not being formed is because the ray required to pass through the optic centre, or the darkened half is not able to..
so I bubbled bright spot</p>

<p>i was so hungry during the test and I couldn't concentrate...my stomach was being way too loud lol and I missed easy ones...that plus the fact that I don't have AP physics and the only physics class in my school doesn't cover a lotta what's on the SAT 2 means that I'm definitely getting below a 600! (and that's being optimistic)</p>

<p>I put there would still be an image. the one with the bird, was it I only--that the bird would look higher? and one with concave lens, could it make all three of those or only I and II?</p>

<p>there was SO MANY of these types of questions:</p>

<p>I only
II only
I and III
II and III</p>

<p>I would look at the correct answer, but then I'd get distracted and kept wondering if it was only I or both I and II or all III.</p>

<p>The conduction question with the plastic wasn't phrased very well. </p>

<p>The cup's width increases by a factor of 4 and then they say the temperature difference is the same? </p>

<p>The temperature difference between the cup's contents and the environment or the temperature difference from final to initial?</p>

<p>Anyways...I put 3 J because a thicker cup would result in better insulation...?</p>

<p>That is what I reasoned also. A thicker cup would provide better insulation and trap the heat better, so I also put 3J. Wow, I practiced with College Board's big book of subject tests, and this one was definitely harder in comparison. Those I,II,III questions were really confusing. I usually get about 63 to 65 raw points on practice tests, but I definitely found this test harder than the practice tests. Any idea what the curve will be like?</p>

<p>Note: The real subject tests are nearly always harder than CB's practice tests. Why would they sell you stuff that would guarantee you high scores; they WANT you to retake over and over so you pay them money.</p>

<p>I found this test pretty much what I expected, but geez, I wish there wasn't so much focus on electricity and magnetism! More thermo, more kinematics, more atomic/nuclear, more relativity even... just not E&M, the two subjects I do worst in.</p>

<p>How does this sound?</p>

<p>Power =E/t.</p>

<p>If the temp difference is the same and there was a times 4 increase in mass (I'm not sure about this),
4E=(4mass)(specific heat is the same)(temp difference is the same)</p>

<p>Final formula:</p>

<p>P=4E/t, or 4P=E/t.</p>

<p>The answer would then be 48 Joules. My first thought was to put 3 Joules but I then considered what i wrote. I'm not sure about the mass times four issue though.</p>

<p>Regarding what Vivi said, I was surprised to find so little test content about modern physics, waves, and heat related subjects. Most of the test was hated electromagnetism and blessed Newton's laws. Though we would expect more of Newton then of electromagnetism, it seems this actually never happens.</p>

<p>does any one remember some of the answer choices to the plastic cup/ conduction question? </p>

<p>the electroscope question with negative particles on the individual leaflets was a struggle for me. i concluded that the rod was postively charged, which would cause the leaflets to fold inward.</p>

<p>I said the rod was positively charged too.</p>

<p>I don't remember what I put for the cup question, but it wasn't 3 J so I got it wrong =|</p>

<p>Hey all, I'm posting from Thailand...I found the test well...tough! But come on, all official Physics tests are expected to be hard. The problem with this test though was that there were so many tricks...especially for all those I, II, III and IV questions. But if u had prepared using the Barron's Prep Book u wud have got enuf prep on those sorts of questions. Mind u...this dunt mean that i did well either.</p>

<p>As for the plastic cup question, dat was one of the dodgy questions...but this is how i reasoned it...
the question asked for what the power of the energy loss of the liquid INSIDE the cup would be
E = mc(T2-T1) but they specifically said that the temp difference was the same....similarly the mass of the LIQUID stayed the same, thus the the energy lost was the SAME. we were supposed to infer that the same amount of time was used and because P = E/t the power of the transfer would also have been the same.</p>

<p>There were many other tricks. I left 5, defn got quite a few here and there wrong, but nething above 750 n me's laughin...</p>

<p>what's the curve? 63+=800?</p>

<p>Guru, where did you fit in the 4 times increase in thickness? I equaled it to 4 times increase in mass, though I'm not sure about that. In any case a change in mass would have a change in energy as I wrote before.</p>