<p>It's been 48 hours, so we can now discuss the free response.</p>
<p>I didn't understand the third question (electrostatics). For part A I said the charge was positive because it had to have been opposite of the other charge. Is that right? I also had no clue how to calculate the force of that charge, so I just wrote down that it had the same charge as the other one.</p>
<p>Also, how was the last section of question 4 solved? It was the one where two index of refractions were given and asked for the distance the oil must be or something.</p>
<p>the electrostatic one was positive, then to get the charge you had to the electric field of both particles, set it equal to zero, and then bring one of the equations to the other side, and the charge ended up being something like 4x10^(something), then to calculate the force it was the charge u found times the charge of the other particle over the distance squared, and to the left cause it was a positive so it attracted the negative charge. Then to calculate the other part is too complicated to explain by words, and part e was 0 cause the potential is 0 at that point.</p>
<p>The key to the experiment one was the 11 students.</p>
<p>I drew a diagram of the track, with one student standing 10+ meters away from the other one. There were 11 students lined up from start to finish, spaced 10 meters apart. They each held a timer (first one held the starting pistol). First one pulled the trigger, everyone started their timer at the same time, and then stopped it when the runner crossed their corresponding line.</p>
<p>It wouldn't give accurate data because of human error and not being able to find the instantaneous acceleration, but I think it was the only way to do that experiment.</p>
<p>if you did it that way, youd also have to take into account the fact that the person standing like 100 meters away would hear the pistol later than the people in front</p>
<p>For the Thermodynamics question, how did you go about finding...everything? Were the temperatures lower, higher than the original? Was heat added? How much?</p>
<p>Temperature was found using P1<em>V1/T1=P2</em>V2/T2. This is gotten from PV=nRT (since R and T are constant). Pressure and volume are given on the graph, and I think you were given a temperature value, so just rearrange and solve for T2. I think I got a negative value for work done (which is the area of the curve, I think), which meant that the heat was added.
We see this from change in U=W + Q
U was 0 because it was a closed system, so W=-Q. Since W was negative, Q had to be positive, so heat had to have been added. I don't know if that's right though; it was one of the questions I wasn't sure on.</p>
<p>Negative value for work? I thought the cycle was counterclockwise - thus the enviroment is doing work on the system, and adding positive work. I'm not sure though - "Damn chemists, they screwed up the signs" as my Physics teacher would say.</p>
<p>Might have been negative. I didn't really study Thermodynamics so I guessed on most of the stuff in that section. Pretty much all of the problems I remembered doing involving work had work yielding a negative value, so I sort of assumed it was negative.</p>
<p>meh, they can't screw us over for mere signs; we got the concepts right and maybe it'll only be a point. I could've sworn the cycle was ccw though...</p>
<p>So if I remember right, either the Volume or Pressure was increased at both point B and C. That would mean the temperature would be less than the 333k or whatever it was originally, right?</p>
<p>for the race experiment, i said that the 10 people would be lined up along the track and every second the man would the timer would call out and whoever was up would to the best of their ability put the piece of masking tape down where they judged the runner to be at the second mark. Once every1 put the markers down the distances would be measured a distance v time graph would be ploteted ect...
Of course it couldent work cause of human error, but im wondering how much credit it will recive if it was described perfectly</p>
<p>also if i had about 50/70 on part 1. And everything on part two correct except for the oil index thingy, and the 2nd to last part of electrostatics, plus acounting for a few minor errors. is there shot at a 5?</p>
<p>Lindsay the experiment you described will get little to no credit. The whole purpose of the experiment is to plot distance vs time, finding the slopes of those to find the velocity vs time, and using that graph to find the points of uniform acceleration. aputzer613 got right the idea for the experiment. Yes according to those numbers you should get a 5 as well.</p>
<p>Question: In the table for finding the index of refraction what did you guys put in for the last two columns?</p>
<p>My experiment could find distance vs. time.</p>
<p>Person 1 stands 10 meters from the start line, person 2 stands 20 meters from the start line, etc. When the runner passes line 1, person 1 hits the timer, and records time 1. When the runner passes line 2, person 2 hits the timer, and records time 2. This is done until time 10, when the runner is 100 meters away from the starting point. </p>
<p>I can then graph distance vs time, distance being 0, 10, 20...100, and time being 0, t1, t2...t10. This would give me a graph of being parabolic at first, but eventually linear. The point at which the graph becomes linear is t(u).</p>
<p>It might be more accurate to collect data the other way, but it isn't logical to have students run after a sprinter and put tape where he lands at each second. I thought the 11 students was a clue to doing it my way.</p>