<p>I said it wasn’t possible to know given the information, but not sure…</p>
<p>The 2009 exam was soo much easier, in my opinion.</p>
<p>Number 1 was, by consensus, easy. Slopes=acc. Distance=area. Total work=change in Kinetic energy, negative force due to negative acceleration
Number 2: Potential in sphere=potential on edge=kQ/R; potential outside sphere=kQ/D, where D is distance from center. Graph for both is line followed by decreasing with the square
Number 3: The single slit formula trivialized it, but most did not know it
Number 4: Weight=weight of water and beaker; Buoy=tension+mg, pressure=pgh(ignoring atm pressure), level lowers
Number 5: mg=Vq/d, solve for whatever; gap since it’s between 1 and 2 electrons, travels in circle in mag field, direction implies charge, Bqv=mv^2/r, where r is less than L/4
Number 6: Difference in energies, multiply by something to get in joules, divide by h and divide c by answer to get wavelength, find if KE of electron is greater or less than energy difference, find wavelength of a 3 eV photon, see what range it’s in</p>
<p>@rawksforgod, i got the same as you. i set the gravitational potential energy equal to the electric gravitational energy, so mgh=qV so h=L and q=(mgL)/V.</p>
<p>For the last part of the question, solving for B, did anyone get (2mv)/(qL)? I set centripetal force equal to magnetic force (qvB) and substituted r for L/2.</p>
<p>@cortana</p>
<p>That’s what I got.</p>
<p>^r=L/4, not L/2. The extent of the magnetic field was L/2, and that must be the DIAMETER of the circle.</p>
<p>why exactly does the water level lower </p>
<p>and for number 2…isnt it kq/r^2 for the second part?</p>
<p>I COMPLETELY botched #2 and #5</p>
<p>Multiple Choice was all right (many conceptual questions)
FRQ were all right. I could answer half of them with confidence. The other half were sort of BS</p>
<p>crap…you’re right. Will i get credit for the description of the motion of the particle when the magnetic field is applied if i said it would curve to the left or right depending on the charge? I didn’t explicitly state it would travel in a circle but i said it would curve.</p>
<p>@rasberry, the water level is lower because water is displaced by the volume of the ball above the surface of the water.</p>
<p>This test was so hard. I was never really good at physics though so…
For FRQ number 6,
Why is the answer for part a q= mgL/V?
That is what I put as well initially until I saw that there was it was moving at constant speed, so there was no acceleration. Thus, if there is no acceleration, shouldn’t there be no g? That was my logic and so I changed my answer at the very last minute. Ahhh, I hate physics! I don’t know why I chose to take the AP…</p>
<p>@raspberry: I forgot the electric field part; yeah: it’s that outside and 0 inside the sphere.</p>
<p>i feel like they should give points for saying that it rotated towards the left or right 
i put that down as well</p>
<p>as for the B formula for #5 is it okay to put Bqv or B = (insert forumla)/qv</p>
<p>I put B>(formula); technically, if there is equality, it will JUST touch, but I doubt that’ll matter.</p>
<p>so the electric field inside the sphere was 0? I was debating between whether the electric field or the electric potential was 0 but i went with the sphere.</p>
<p>On the single slit diffraction I did it correct, but how could they say that using a ruler is incorrect? Isn’t it technically correct?</p>
<p>Zach321 I believe its correct</p>
<p>@cortana: potential is the integral of the field, so it can be nonzero.</p>
<p>I think the using the ruler thing is like answering “Does not include Alaska and Hawaii” on a Human Geo question about why a map of the continental US does not accurately represent religion in the United States; that was not an accepted answer.</p>
<p>isnt the electric field kQ/r^2 so can’t you just plug in the numbers? or is it zero for both those parts…darn</p>