Physics January 2011

<p>It was fundamental frequency for the buzzing sound. Beats are something entirely different.
^are you sure? ughh I put resonance.</p>

<p>

magnification = pos of image/ pos of object</p>

<p>I think I remember it being 3. Maybe that’s just a random number popping into my head.</p>

<p>@jimmei:
For #1: i think that u r correct. The V to SA ratio determines when a freely falling object will hit terminal velocity.</p>

<p>did the question ask for magnification, or the actual diameter?</p>

<p>

</p>

<p>I put that also.</p>

<p>I don’t think it gave you the diameter. I think all it asked for was magnification, which was 6.</p>

<p>Two answers for two questions in Part A was (according to me): electron and quarks.
^do you remember what the questions were?</p>

<p>There was one where they told u 1 electron = 1,6 <em>10^-19 C. So how many electrons per second flow in a current of 1,6 A? 1,6 A equals 1,6 C per second. So 6,2</em>10^18 electrons make up 1C. So 1,6 C would be: 1,6<em>6,2</em>10^18e = 10^19 e??? Not sure if its right.</p>

<p>@ jimmei:
6. last, what about the…question about the rod? the choices were like…negat
ive/positive, neutral and grounded…etc</p>

<p>I put negative. In the spectrometer (or whatever?) it is only the free electrons that can move. So if the leaves are repelling each other, that means that they are negetively charged. The free electrons will only come from the top of the device if they are repelled by a rod that has the same charge: that is, negative.</p>

<p>Compiled Answers
-Universe expansion: red shift + something else, I & II
-Oil drop: calculate electron charge
-Ice cube -50 C to 150 C:
… _<em>/
… /
.</em>/
/
-Initial velocity 30 m/s, v and a at apex: 0 m/s, -10 m/s^2
-Initial velocity 30 m/s, v and a final: 30 m/s, -10 m/s^2
-X and Y collision: need to know masses (was this the same as ratio of the masses?)
-Insulator/conductor: glass and aluminum
-Starting a fire: converging lens
-Cop car moving: fA < f0, fB > f0
-People moving: fA > f0, fB < f0
-Heavy ball versus lighter ball: I put ratio of V to SA was smaller in the larger ball
-Lightest particle: electron (I just googled this)
-Magnification of diameter of coin: 6 (choice A)
-Buzzing noise: ???
-Ball going east, force applied to it: went east, curved, and carried on this way diagonally southwest
-Why doesn’t moon crash into earth: Constant gravitational pull, but the velocity keeps it from crashing</p>

<p>There was also one question where they put a graph of (symbol of alpha) 1/r^2, and asked u about which of the following magnitudes did not follow such a pattern. I put potential energy/difference of a particle/planet.</p>

<p>The question involved the two leaves coming back together. They were already apart from each other, because the spectrometer was positively charged. I put the answer as negative conductor, that way the charges would even out and the leaves would move back together.</p>

<p>I put negative. In the spectrometer (or whatever?) it is only the free electrons that can move. So if the leaves are repelling each other, that means that they are negetively charged. The free electrons will only come from the top of the device if they are repelled by a rod that has the same charge: that is, negative.</p>

<p>^Yeah, pretty sure I put negative. If we’re talking about the same question…electroscope with leaves, a bunch of plus signs?</p>

<p>@jimey1337 add this:Another one asked how to maximize the magnetic force. answer was I II and III. (velocity of particle, charge of particle and magnitude of magnetic field)</p>

<p>^Agreed with the maximize magnetic force one</p>

<p>Compiled Answers
-Universe expansion: red shift + something else, I & II
-Oil drop: calculate electron charge
-Ice cube -50 C to 150 C:
… _<em>/
… /
.</em>/
/
-Initial velocity 30 m/s, v and a at apex: 0 m/s, -10 m/s^2
-Initial velocity 30 m/s, v and a final: 30 m/s, -10 m/s^2
-X and Y collision: need to know masses (was this the same as ratio of the masses?)
-Insulator/conductor: glass and aluminum
-Starting a fire: converging lens
-Cop car moving: fA < f0, fB > f0
-People moving: fA > f0, fB < f0
-Heavy ball versus lighter ball: I put ratio of V to SA was smaller in the larger ball
-Lightest particle: electron (I just googled this)
-Magnification of diameter of coin: 6 (choice A)
-Buzzing noise: ???
-Ball going east, force applied to it: went east, curved, and carried on this way diagonally southwest
-Why doesn’t moon crash into earth: Constant gravitational pull, but the velocity keeps it from crashing
-Electroscope, what was the rod’s charge: negative
-Which one didn’t have a 1/r^2 graph: potential energy of charge
-Maximize magnetic force: I, II, and III (velocity of particle, charge of particle and magnitude of magnetic field)</p>

<p>@ Xanedrin: Yeah, that was easy. Straight from the formula: F = qvB
@jimmeii: we are talking about the same question :)</p>

<p>Is there a consensus on the buzzing question yet?
(choices include: resonance, beats, fundamental frequency, etc.)</p>

<p>Somewhere at the beginning, I got 2 answers of 160 N
something to do with moon and earth’s gravity</p>

<p>It was a pretty easy question, but I might’ve been careless. Any comments?</p>

<p>I’m almost certain the buzzing sound comes from fundamental frequency characteristics. It’s definitely not beats, and after looking up resonance, it doesn’t seem like that’s the answer.</p>