MAY 2010 Physics

<p>Good luck everyone!</p>

<p>So the embargo’s lifted, guys. Let’s discuss.</p>

<p>I think it was pretty hard??? LOOTTS of Wave questions -__-</p>

<p>What did you guys put for the transformer question?</p>

<p>And was there current induced in the wire that was moving through a uniform magnetic field? I said there wasn’t.</p>

<p>I think i put A for the transformer…
Honestly, it’s way too conceptual than i was expected… I probably got 20+ wrongs…</p>

<p>It wasn’t A. I think it talked about inducing voltage in the second resistor due to AC current in the first.</p>

<p>The one with the square loop has no induced voltage, since dphi/dt = 0.</p>

<p>pseudoreal, the one that talked about inducing voltage in the 2nd resistor due to AC current in the first was B. Is that right?</p>

<p>Etherreality3, does your answer refer to pseudoreal? there was no current?</p>

<p>Yes to both.</p>

<p>Also, what did you guys say for the one about changing what about a string will affect the fundamental frequency of a string? I think i put A, tension.</p>

<p>What did you guys say for the work/electric potential questions? The one with the charge Q in the middle and the little q on the outside? Did the circle going around Q represent an equipotential? (please tell me it does…)</p>

<p>What about the one with the resistor/bulb/solar panel? Was that one asking which one is used to store energy? I said only resistor…</p>

<p>Tension was right.</p>

<p>The circle was equipotential.</p>

<p>Resistor was wrong. Resistors use electrical energy. It was a solar cell.</p>

<p>I put A, tension too…
Everything equal distance around Q should be equipotential i think.
I said only solar panel.
How do we cancel score?</p>

<p>^
pseudoreal</p>

<p>You are really good… Have you done USPhO before?</p>

<p>So, in regards to the equipotential question, do you remember what 14-16 were?</p>

<p>14 was asking about which one did the most work, right? It was the first one that got closer to the charge Q, correct?</p>

<ol>
<li>No work? the ones that went around the potential line…</li>
</ol>

<p>16, electric potential change? which one was that one…</p>

<p>and what was that question on with the solar panel? do you remember the question?</p>

<p>any other hard ones that we’re missing?</p>

<p>pseudoreal, in addition to solar cell, was the second option on that question also correct? I can’t remember what it was, but it was a I,II,III, I and II, II and III kind of question…</p>

<p>The other thing was an incandescent light bulb. That was wrong because it uses electric energy and transforms it into light.</p>

<p>14) most work is the first one only
15) no work was b and c
16) also b and c if I remember correctly because V = kq/d and since the distance between the charges for b and c were the same, it should be the same answer as 15</p>

<p>regarding the fundamental frequency question, i believe it was L because the formula for frequency on a string is f = nv/2L. only changing the length will change the frequency… correct me if i’m wrong</p>

<p>Was the question about storing energy? Or what was it about?</p>

<p>What did you say about the astronaut’s weight on the planet with 2M where M is the mass of the earth?</p>

<p>oh that’s right! OH NO i think i put lightbulb in addition to solar cell… what was the answer to the mummy/isotope decay one and the energy/frequency x,y,z graph one? That was 2 parts which… I don’t think I did correctly…</p>