November 2012 SAT Physics Subject Test Discussion

<p>Does anyone know what the curve usually is? I know the college board book says 59/75 for an 800, but that’s only one data point.</p>

<ol>
<li>15 < T < 20</li>
<li>Greater than 0.6c less than c</li>
<li>Two different metals bend because of different specific heat</li>
<li>It was traveling in a circle.</li>
<li>The last one: I and III only. I was true - Kepler’s laws state that two lines drawn from a planet to the sun sweep out equal areas. II was false - the farther away planet does not have a greater velocity; L=mvr and if r is increased v goes down. III was true - the kinetic energy of the closer planet was greater; a greater velocity KE = 0.5MV^2 is therefore greater.</li>
<li>Electrons Ionize in air.</li>
<li>Ball at the beginning of being thrown upward: velocity upward, acceleration downward.</li>
<li>Ball at the top of the path: velocity zero, acceleration downward.</li>
<li>Ball at the end of being thrown: velocity downward, acceleration downward.</li>
<li>Ohm’s law.</li>
<li>Work is not a vector.</li>
<li>Snell did not have to do with Thermo-goddamnits.</li>
<li>Changing the radius from 0.025 to 0.1 made the centripetal force [(1/4)F] as great.</li>
<li>Rutherford, small, massive positively charged nucleus.</li>
<li>Same size inverted.</li>
<li>Momentum always changes when force is applied</li>
<li>The force was 5x10^6</li>
<li>The electric force went from like 4 * 10^4 to 1 * 10^4</li>
<li>Faraday’s law was Teslas * meters^2 / second</li>
<li>Light bulb was out</li>
<li>Light bulb went slowly brighter then stayed bright (might be wrong need explanation)</li>
<li>The distance went to 0.5m instead of 2 m. </li>
<li>Ff was 18</li>
<li>Mu → 1/6</li>
<li>What was the velocity?</li>
<li>Acceleration was 1.3 m/s^2</li>
<li>The first resistor got the most current.</li>
<li>The metal plate looked like a resistor. </li>
<li>Calculating force of North and South thing was zero → F = qvBSin(theta) → Sin(180) = 0.</li>
<li>The impulse question where mv = FdeltaT → I forget the answer. </li>
<li>The 2M block compressed the spring 2x.</li>
<li>The sheet bolted onto the table → harmonic motion. </li>
<li>The planets with radius 2r and mass 2M and stuff – > both choice E. The force is greatest when it was 2M and r and the kinetic energy → KE = msqroot(GM/r) is biggest.</li>
<li>Efficiency was 60% - some say yes, some no.</li>
<li>For the standing wave problem i put the straight one, but i think it was probably one of waves w/ different amplitudes.</li>
<li>Objects cannot approach c because of infinite energy.</li>
<li>For one of the last ones, the electric force on the point outside is greatest when the curve is sharpest. it was the one farthest right i think.</li>
<li>The sound wave vs. light wave one, i think it was the frequency of the light was greater because wavelength was the same and speed of sound is less than c</li>
<li>The electric lines one: Q1 is opposite and greater than Q2</li>
<li>The sun setting was interference?</li>
<li>The prism was refraction</li>
<li>The magnifying glass was reflection or refraction?</li>
<li>PE was lowest</li>
<li>KE was conserved in I, II, and III</li>
<li>Momentum was conserved in I, II</li>
<li>The double slit was decrease and decrease? Can anyone confirm?</li>
<li>(75
2000)/((60)(60))</li>
</ol>

<p>ANY OTHERS?</p>

<ol>
<li>It was C I think or whatever one was on the far right where the shape bent in. </li>
<li>The spectral lines they were of opposite charge and the one the left had a bigger charge.</li>
<li>I said tesla meter^2 second. It asked about Faraday’s law which is the emf equals the change in magflux over time. Magflux = BA so B is the tesla part; the area part is meters squared (I think - anyone want to back me up as I’m bad with math); the seconds part is from the t in the magflux/t equation.</li>
<li>Yes I put the one with mass 2m and r for both the greatest kinetic energy and grav potential force.</li>
<li>It was 2M.</li>
</ol>

<p>Thanks! And if you have any more, fire away.</p>

<ol>
<li>For that one I put interference and that is what other people are saying. I don’t honestly know, though.</li>
<li>It was definitely the first one. Resistors in parallel split the current. </li>
</ol>

<p>43/44 were diagrams of balls colliding. </p>

<p>From looking at the PR review book I think an decrease in the slit is an increase in the bands. **** I missed that.</p>

<p>That would put you around a 700.</p>

<p>What about the questions regarding the potential energy curve? The first question was what the Pe was at a certain point and the second question was what the Ke was at that same point. The answer choices were a, b, a+b, a-b, and b-a I think</p>

<p>why is number 23’s answer mu = 1/6? I thought the block had a frictional force of 2 N and a normal force of F<em>N = F</em>g - 12 N = 38 N, so F<em>fr = mu * F</em>N and mu = F<em>fr/F</em>N = 2/38 = 1/19?</p>

<p>For the resistance question, it gave you a circuit with Voltage V and asked in which resistor was the current greatest. R1 was in series with R2, R3, and R4, but R2 was in parallel with R3 and R4, which were in series with each other (if that makes any sense). It also said the resistance in each resistor was the same. I’d also like to know the answer to this one.</p>

<p>For the PE vs. t curve, it asked 1.) what is the PE at a certain point greater than zero, and 2.) what is the KE at that same point? At that point, the height from PE=0 to the curve was a and the height from the curve to the line representing total energy was b (or maybe they were reversed). Anyways, the height from the x-axis to the curve was the PE at that point, and the height from the curve to the total energy line was the KE at the same point.</p>

<p>For the red light at sunrise/sunset, the correct answer is scattering. I put polarization too, but I checked after the test and it is actually scattering.</p>

<p>Oh, and approximately what do you guys think 15-20 wrong would be if I answered all the questions? 740+ hopefully?</p>

<p>I don’t remember exactly where each letter was. If it was the way I described it in my above post, yes, that’s what I put.</p>

<p>Right. Even with the minimal knowledge of physics I possess, I taught myself enough that I knew those were wrong. ;)</p>

<p>Guys can you tell me what happens when an object reaches the speed of light
I wrote that it dissappears because as the obj approaches speed of light its length decreases and i guess when it finallt reaches speed of light it becomes zero right?
Correct me if i am wrong.</p>

<p>That’s what I put. It was a graph, right?</p>

<p>@asdf1253
I’m not sure maybe you got it right.</p>

<ol>
<li>15 < T < 20</li>
<li>Greater than 0.6c less than c</li>
<li>Two different metals bend because of different specific heat</li>
<li>It was traveling in a circle.</li>
<li>The last one: I and III only. I was true - Kepler’s laws state that two lines drawn from a planet to the sun sweep out equal areas. II was false - the farther away planet does not have a greater velocity; L=mvr and if r is increased v goes down. III was true - the kinetic energy of the closer planet was greater; a greater velocity KE = 0.5MV^2 is therefore greater.</li>
<li>Electrons Ionize in air.</li>
<li>Ball at the beginning of being thrown upward: velocity upward, acceleration downward.</li>
<li>Ball at the top of the path: velocity zero, acceleration downward.</li>
<li>Ball at the end of being thrown: velocity downward, acceleration downward.</li>
<li>Ohm’s law.</li>
<li>Work is not a vector.</li>
<li>Snell did not have to do with Thermo-goddamnits.</li>
<li>Changing the radius from 0.025 to 0.1 made the centripetal force [(1/4)F] as great.</li>
<li>Rutherford, small, massive positively charged nucleus.</li>
<li>Same size inverted.</li>
<li>Momentum always changes when force is applied</li>
<li>The force was 5x10^6</li>
<li>The electric force went from like 4 * 10^4 to 1 * 10^4</li>
<li>Faraday’s law was Teslas * meters^2 / second</li>
<li>Light bulb was out</li>
<li>Light bulb went slowly brighter then stayed bright (might be wrong need explanation)</li>
<li>The distance went to 0.5m instead of 2 m. </li>
<li>Ff was 18</li>
<li>Mu → 1/6</li>
<li>What was the velocity?</li>
<li>Acceleration was 1.3 m/s^2</li>
<li>The first resistor got the most current.</li>
<li>The metal plate looked like a resistor. </li>
<li>Calculating force of North and South thing was zero → F = qvBSin(theta) → Sin(180) = 0.</li>
<li>The impulse question where mv = FdeltaT → I forget the answer. </li>
<li>The 2M block compressed the spring 2x.</li>
<li>The sheet bolted onto the table → harmonic motion. </li>
<li>The planets with radius 2r and mass 2M and stuff – > both choice E. The force is greatest when it was 2M and r and the kinetic energy → KE = msqroot(GM/r) is biggest.</li>
<li>Efficiency was 60% - some say yes, some no.</li>
<li>For the standing wave problem i put the straight one, but i think it was probably one of waves w/ different amplitudes.</li>
<li>Objects cannot approach c because of infinite energy.</li>
<li>For one of the last ones, the electric force on the point outside is greatest when the curve is sharpest. it was the one farthest right i think.</li>
<li>The sound wave vs. light wave one, i think it was the frequency of the light was greater because wavelength was the same and speed of sound is less than c</li>
<li>The electric lines one: Q1 is opposite and greater than Q2</li>
<li>The sun setting was interference?</li>
<li>The prism was refraction</li>
<li>The magnifying glass was reflection or refraction?</li>
<li>PE was lowest</li>
<li>KE was conserved in I, II, and III</li>
<li>Momentum was conserved in I, II</li>
<li>The double slit was decrease and decrease? Can anyone confirm?</li>
<li>(75
2000)/((60)(60))</li>
<li>The planets with radius 2r and mass 2M and stuff – > both choice E. The force is greatest when it was 2M and r and the kinetic energy → KE = m*sqroot(GM/r) is biggest.</li>
</ol>

<p>For the one with the potential energy graph. It was a then b. Or b then a.</p>

<p>@justPhysics, number 3 should be “because they have different coefficients of thermal expansion”, not because of the specific heat. Also, I agree with asdf1253. The coefficient of friction was 1/19. I believe this was also the one with the force at an angle, so you had to factor that into the normal force as well. Not positive that it was this problem, so don’t quote me on that though. But one of the answers was 1/19.</p>

<p>And 34, it was the one with differing amplitudes; the “straight line” wave is possble for a standing wave.</p>

<p>Do you guys think 11 off raw score is a 800 on this test?</p>

<p>What is a good SAT physics score for top tech schools ?</p>

<p>@dudgeguy1811, definitely. a 64/75 should be an 800 (IMO, based off other scales and practice tests).
@laituan245, it depends. The curve is considered by some to be easy enough that an 800 seems to practically be “required”, but typically a 750+ is good enough for most, if not all top schools. 770+ to be safe.</p>

<p>yeah that’s wat I thought too… but Im cutting it very close… all careless mistakes…</p>