Dec 3 Physics Official Thread

<p>dood, the blob question near the end with the test points. that was hard.</p>

<p>I didn't get to that question...I thought I had around minutes left by number 70, but the proctor called the time. I can't believe I used my left hand for the right hand rule though. I missed such an easy question because of that.</p>

<p>Can someone answer #73? There's a battery and it's been running for .5 hours. There is a current of 2 Amps going through it. How many coulombs passed through the battery. I completely zoned out on this one. I left it blank. I can rememeber a few answer choices I thikn the lowests are around 1800 and the highest was like 40000 or something.</p>

<p>3600 C I think.</p>

<p>yes, move that charge 2 cm to the right so you have 3 cm on each side</p>

<p>guitar strings: wavelength is the only one that changes</p>

<p>Correction to Joethemole: Wavelength is the only one that DOES NOT change.</p>

<p>Agree. Frequency changes.</p>

<p>For Charges on the wierd shaped conductor, I put narrow point as strongest field. </p>

<p>The field around a charged conductor
A conductor is in electrostatic equilibrium when the charge distribution (the way the charge is distributed over the conductor) is fixed. Basically, when you charge a conductor the charge spreads itself out. At equilibrium, the charge and electric field follow these guidelines:</p>

<p>the excess charge lies only at the surface of the conductor
the electric field is zero within the solid part of the conductor
the electric field at the surface of the conductor is perpendicular to the surface
charge accumulates, and the field is strongest, on pointy parts of the conductor</p>

<p>There was a sub-section with a ke-time graph and five intervals A, B, C, D, E. One question gave a set of conditions of interval A and asked which was true. Does anyone remember the answer?</p>

<p>3600 C is correct for #73, since 1 A = 1 C/s
2A X 1800 s = 3600 C.</p>

<p>I thought this was WAY better than the PR and Sparknotes practice tests. Heck those were hard. This test was also a bit easier than the Real test, but I'm thinking the curve will still be about the same (>63-65 = 800). I had some wrong on waves and electricity/magnetism but I hope it still turns out to be 800 =/</p>

<p>So far i remember those questions, anyone adds yours...?</p>

<ol>
<li> Expanding universe ==> The red-shift and background radiation applies
but not elliptical orbit.</li>
<li> Half lives question ==> 1 Hour 20 Minutes,</li>
<li> Photoelectric One ==></li>
<li> The question with magnetic field and turning square==> 2 of them,</li>
<li> Question with photon shot to something and electron comes out. if the
second electron has half the wavelength, the energy-volt should be
==> Double Energy,</li>
<li> Charges A and B shot horizontally into a field ==> Same sign of charge,</li>
<li> Weird shape and ask which field was strongest==> Narrowed Point,</li>
<li> Kite with tension/wind question: 500.</li>
<li> Presure on surface of boiling water: Same with room air presure,</li>
<li>Quitar strings ==> Tension and frequency change not wavelength,</li>
<li>Good insulator and conductor ==> Glass and aluminum,</li>
<li>Magnetic flux one ==> </li>
<li>Battery and it's been running for .5 hours ==> 3600 C,</li>
<li>Move that charge ==> 2cm,</li>
<li>Galvanometer thing ==></li>
</ol>

<p>which particle is deflected more, x or y, (y had a greater deflection i think) bec y? </p>

<p>a) x has more mass
b) y has more mass
c) x has more charge
d) y has more charge
e) i can't remember ><</p>

<p>regarding the two charges......i believe that they entered the field with the same speed......so the answer should be larger charge, easier to deflect.....</p>

<p>photoelectric effect.....i believe that the intensity wasn't changed the frequency of the light was increased....the emitted electrons would be more energetic...</p>

<p>elmy, it said the charges entered at DIFFERENT speeds, so the only definite thing we know is that they both have the same sign of charge.</p>

<p>What about that spaceship one going 0.6 c with another in the opposite direction going the same speed?</p>

<p>Did they really have different speeds? I got that one wrong then.<br>
The spaceship one was c because nothing can move faster than the speed of light (it would have been 1.2c otherwise).</p>

<p>Dang elmy. You about gave me a heart attack :-). What were the three choices on the photoelectric one? Wave function and two others...</p>

<p>For the glass/aluminum one, wasn't there another choice with rubber and another metal (possibly copper)? What makes glass and aluminum so much better?</p>

<ol>
<li>Expanding universe ==> The red-shift and background radiation applies
but not elliptical orbit.</li>
<li>Half lives question ==> 1 Hour 20 Minutes,</li>
<li>Photoelectric One ==> the intensity wasn't changed but frequency increased and electrons more energetic,</li>
<li>The question with magnetic field and turning square==> 2 of them,</li>
<li>Question with photon shot to something and electron comes out. if the
second electron has half the wavelength, the energy-volt should be
==> Double Energy,</li>
<li>Charges A and B shot horizontally into a field ==> Same sign of charge,</li>
<li>Weird shape and ask which field was strongest==> Narrowed Point,</li>
<li>Kite with tension/wind question: 500.</li>
<li>Presure on surface of boiling water: Same with room air presure,</li>
<li>Quitar strings ==> Tension and frequency change not wavelength,</li>
<li>Good insulator and conductor ==> Glass and aluminum,</li>
<li>Magnetic flux one ==> </li>
<li>Battery and it's been running for .5 hours ==> 3600 C,</li>
<li>Move that charge ==> 2cm,</li>
<li>Galvanometer thing ==></li>
<li>One spaceship 0.6c and other 0.6c opposite ==> between 0.6c and 1C,</li>
</ol>

<ol>
<li>Expanding universe ==> The red-shift and background radiation applies
but not elliptical orbit.</li>
<li>Half lives question ==> 1 Hour 20 Minutes,</li>
<li>Photoelectric One ==> the intensity wasn't changed but frequency increased and electrons more energetic,</li>
<li>The question with magnetic field and turning square==> 2 of them,</li>
<li>Question with photon shot to something and electron comes out. if the
second electron has half the wavelength, the energy-volt should be
==> Double Energy,</li>
<li>Charges A and B shot horizontally into a field ==> Same sign of charge,</li>
<li>Weird shape and ask which field was strongest==> Narrowed Point,</li>
<li>Kite with tension/wind question: 500.</li>
<li>Presure on surface of boiling water: Same with room air presure,</li>
<li>Guitar strings ==> Tension and frequency change not wavelength,</li>
<li>Good insulator and conductor ==> Glass and aluminum,</li>
<li>Magnetic flux one ==> </li>
<li>Battery and it's been running for .5 hours ==> 3600 C,</li>
<li>Move that charge ==> 2cm,</li>
<li>Galvanometer thing ==></li>
<li>One spaceship 0.6c and other 0.6c opposite ==> between 0.6c and 1C,</li>
<li>Plane Mirror, Choice Among given images ==> Same distance,</li>
</ol>

<p>The plane mirror one was the same distance and left/right reversed, right?</p>

<p>Some question about the force on a charge btw 2 plates with voltage V and distance d....you had to do E = V/d, then F = Eq. The answer was 2 * 10^3.</p>

<p>I remember several questions that haven't been listed yet. These aren't the exact wordings; I'm just paraphrasing.</p>

<p>Q: What quality causes waves to diffract differently?
A: wavelength</p>

<p>Q: At what point in a pendulum's swing is the tension in the string the greatest?
A: at its lowest point</p>

<p>Q: A person walks 40m east, 20m north, and then 20m west. What is his displacement from the starting point?
A: 28m, 45 degrees NofE </p>

<p>Q: Which graph shows the velocity vs time of a free falling object due to earth's gravity (ignore air resistance)?
A: linear graph going through origin</p>

<p>Q: Which graph shows the force of gravity vs distance of two objects?
A: inverse relation graph</p>

<p>Q: Object swinging in circular motion. Which direction will the object's velocity be if the string breaks?
A: tangent to circular path </p>

<p>The galvanometer question was weird. I just looked at the drawing and was like WTH, and then skipped it.</p>

<p>Keep the list going. Maybe I'll figure out my score before they send the report. =/</p>