Sofia. Posted May 10, 2015 Report Share Posted May 10, 2015 Huh. Can't remember, sorry! Reply Link to post Share on other sites More sharing options...
Hassan76 Posted May 10, 2015 Report Share Posted May 10, 2015 No problem, hope you gained the marks, but how did you answer the question on the masses a and B, how did you prove that they are the same Reply Link to post Share on other sites More sharing options...
Sofia. Posted May 10, 2015 Report Share Posted May 10, 2015 Ah, I can't remember that either. It had something to do with equating two equations, where k and w was the same so m had to be the same. What was the formula you had to prove before that? Reply Link to post Share on other sites More sharing options...
Hassan76 Posted May 10, 2015 Report Share Posted May 10, 2015 W squared = k/ mA=- w^2 xF= ma, F=-K xEquating gives K/m= - a/xK/m= - -w^2 x/xSo k/m = w^2 Reply Link to post Share on other sites More sharing options...
Sofia. Posted May 10, 2015 Report Share Posted May 10, 2015 Since k is constant (springs were made of the similar material), and w is constant (time period the same), then mass had to be constant. Reply Link to post Share on other sites More sharing options...
Hassan76 Posted May 10, 2015 Report Share Posted May 10, 2015 I said w is constant but forgot to relate it to period easy lost marks Reply Link to post Share on other sites More sharing options...
Hassan76 Posted May 10, 2015 Report Share Posted May 10, 2015 I wish paper 3 comes very hard so that the 7 is from 35/60, it happened in M11, Reply Link to post Share on other sites More sharing options...
Ossih Posted May 10, 2015 Report Share Posted May 10, 2015 no but that's what im saying, its not the case of 10 electrons passing through that ammeter in 0.5s. Each individual electron is faster BUT the time after which each electron whizzes off is the same, because there's a one-to-one instantaneous correspondence between a photon hitting and an electron hitting. What I'm saying is that initially, each of those 10 electrons travelled at say 1m/s and travelled say 12m of wire. Each electron was shot with a delay of 1s in between them. Now, those same electrons are travelling at 2m/s, still travelling 12m of wire, still a 1s delay between them. Just the shots are faster, but the overall movement of charge isn't faster itself! Do you get what I'm trying to say haha. I can't think of a good analogy. It's a matter of firing faster bullets and slower bullets, but the time interval between bullets is the same, so overall, the number of bullets per unit time is the same. Alright, let's consider that situation that you've set up. But i'll fix it a bit to fit my diagrams. So we will suppose that we will fire 6 electrons at 1m/s through a 4-meter wire, with a 1s delay between each electron. This can be represented by this diagram:Untitled.png Notice that the electrons are meant to be positioned just a bit before their respective positions. In other words, for t = 0 at p2, the electron e3 is a bit before that position p2.So from the diagram, during 1s-interval, only e3 has passed through p2, which means that the current is 1 electron charge per second (or 1e Amps). Let's now increase the speed by 2, we'll get the diagram:Untitled - Copy (2).png In this diagram, during 1s-interval, both e3 & e4 have passed through p2, which means that the current is 2 electron charge per second (or 2e Amps).So whatever situation you set up, when you increase kinetic energy (i.e. speed) of the electrons, the current will increase I'm sorry haha i'm just feeling really stubbornly about what I said I understand everything you say but I can't help but feeling that my explanation makes sense too. Oh well We'll find out soon enough haha. Thanks so much though Sofia and Ossih, I strongly feel that tomorrow they will get a question on Olber's paradox and the parallax method, and Take care of the definition like comet is icy/rocky body orbiting the sun in highly elliptical orbit, asteroid-minor planet between the orbits of Mars and Jupiter , take care of the order of planets from the sun, and order of their sizes, the class Oh Be A Fine Girl/Guy Kiss Me, look for this I simply the temperatures,Just memorize the the lower limit except for the first oneAnd add *100 to the numbersO. 280 -500B 99-280.A-74-99F-60-74G-49-60K-35-49M-20-35And for the colors it is very simple :You start with a couloir alone, the next stage is that coulour and another, than this 2nd color alone and so onSo blueBlue whiteWhiteYellow whiteYellowOrangeOrange redThat's really helpful. Thanks man! Reply Link to post Share on other sites More sharing options...
Hassan76 Posted May 10, 2015 Report Share Posted May 10, 2015 Ur welcome man, here are some notes for relativity https://wsscience.wikispaces.com/file/view/IB%20HL%20STUDY%20GUIDE%20ORGANIZER-RELATIVITY.pdf/454055778/IB%20HL%20STUDY%20GUIDE%20ORGANIZER-RELATIVITY.pdf Reply Link to post Share on other sites More sharing options...
Megamind Posted May 11, 2015 Report Share Posted May 11, 2015 (edited) I wish paper 3 comes very hard so that the 7 is from 35/60, it happened in M11, Even if the boundaries do change for each paper, I don't understand how that really affects the final grade too much. I mean the percentage needed for a 7 in physics hardly ever fluctuates from around 70-73%. The weightage from your marks in each paper and the IA is what is added to make your final grade right, I don't understand why they issue a grade for each paper and IA?? What do you say, Sofia, Hassan and Ossih? Edited May 11, 2015 by Megamind Reply Link to post Share on other sites More sharing options...
ALithuanian Posted May 11, 2015 Report Share Posted May 11, 2015 I wish paper 3 comes very hard so that the 7 is from 35/60, it happened in M11, Even if the boundaries do change for each paper, I don't understand how that really affects the final grade too much. I mean the percentage needed for a 7 in physics hardly ever fluctuates from around 70-73%. The weightage from your marks in each paper and the IA is what is added to make your final grade right, I don't understand why they issue a grade for each paper and IA?? What do you say, Sofia, Hassan and Ossih? I'm not one of them, but from what I heard that's what happens:1) different teams grade different papers (p1, p2, p3) separately2) after grading everyone's exams in that particular paper the team reads through grade descriptors + looks at past papers and evaluates what should be the grade for that particular paper3) grade boundaries of all separate papers are weighted and then added up to display the combined/total/final grade boundaries for the subject. Hence they issue separate grade boundaries for each paper to create a combined grade boundary4) after all that, your points in papers + IA are converted to percentages according to their weight, added up and evaluated against the combined/total/final grade boundary. Hence, even if you do horribly in one paper you can get a 7 if you score high marks in other papers.In other words, they do not use interim grades of each paper for your final grade calculation directly, but they do play a role in shaping the combined grade boundary. 2 Reply Link to post Share on other sites More sharing options...
Hassan76 Posted May 11, 2015 Report Share Posted May 11, 2015 (edited) Look, let's say here are the boundaries for the 7 for each component, ia, paper 1, paper 2, paper 3 HLIa: it is always 39/48, and they are worth 24% so 19.5 pointsPaper 1: 32/40, and it is worth 20% so 16 pointsPaper 2: 68/95 and it is worth 36% so 68* 36/95 gives 25.7Paper 3: 46/60 and it is worth 20% so 46/3 which gives 15.3 pointsThe total is 76.5 so it will be 77 or max 78, an dI've tried this with last hear's boundaries and it worked, but the boundaries for physics didn't ever exceed 75% These boundaries are just examples. Edited May 11, 2015 by Hassan76 Reply Link to post Share on other sites More sharing options...
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