Apple Posted May 8, 2016 Report Share Posted May 8, 2016 14 minutes ago, ibstudent081099 said: A question, isn't the percentage uncertainty the fractional uncertainty multiplied by 100? Yep. Reply Link to post Share on other sites More sharing options...
ibstudent081099 Posted May 8, 2016 Report Share Posted May 8, 2016 (edited) 33 minutes ago, Apple said: Yep. Because for the question on the percentage uncertainty I chose the answer with pi because multiplying by the volume that is what I got. If anyone could tell me whether this is wrong I would really appreciate it (I wouldn't like to repeat the mistake tomorrow). Thanks Edited May 8, 2016 by ibstudent081099 Reply Link to post Share on other sites More sharing options...
rakinator Posted May 8, 2016 Report Share Posted May 8, 2016 1 hour ago, ibstudent081099 said: Because for the question on the percentage uncertainty I chose the answer with pi because multiplying by the volume that is what I got. If anyone could tell me whether this is wrong I would really appreciate it (I wouldn't like to repeat the mistake tomorrow). Thanks 2 Lol I picked the one that had pi because I didn't have time to work out that one. Most of my class would finish practice paper 1's in like 25-35 mins and none of us were done when they called time. And I remember now that I picked the normal curve too since the value of cos increases till pi/4 and then decreases on the interval [pi/4, pi/2] For the emf question on paper 2 were you supposed to state the voltage when the current was 0 (I think I wrote down 9.2V?) Reply Link to post Share on other sites More sharing options...
nina101 Posted May 8, 2016 Report Share Posted May 8, 2016 2 hours ago, rakinator said: Lol I picked the one that had pi because I didn't have time to work out that one. Most of my class would finish practice paper 1's in like 25-35 mins and none of us were done when they called time. And I remember now that I picked the normal curve too since the value of cos increases till pi/4 and then decreases on the interval [pi/4, pi/2] For the emf question on paper 2 were you supposed to state the voltage when the current was 0 (I think I wrote down 9.2V?) Yes, thats what you had to do for the emf question. Reply Link to post Share on other sites More sharing options...
Apple Posted May 8, 2016 Report Share Posted May 8, 2016 3 hours ago, nina101 said: Yes, thats what you had to do for the emf question. 6 hours ago, rakinator said: Lol I picked the one that had pi because I didn't have time to work out that one. Most of my class would finish practice paper 1's in like 25-35 mins and none of us were done when they called time. And I remember now that I picked the normal curve too since the value of cos increases till pi/4 and then decreases on the interval [pi/4, pi/2] For the emf question on paper 2 were you supposed to state the voltage when the current was 0 (I think I wrote down 9.2V?) What did you guys get for the efficiency of the motor in the last sub-question of no.1? Reply Link to post Share on other sites More sharing options...
rakinator Posted May 8, 2016 Report Share Posted May 8, 2016 1 minute ago, Apple said: What did you guys get for the efficiency of the motor in the last sub-question of no.1? I think I got 0.55 or something around there. Reply Link to post Share on other sites More sharing options...
Apple Posted May 9, 2016 Report Share Posted May 9, 2016 3 hours ago, rakinator said: I think I got 0.55 or something around there. Same here! Reply Link to post Share on other sites More sharing options...
Ana Lau Posted May 9, 2016 Report Share Posted May 9, 2016 23 hours ago, Andrew said: I kept asking myself why I didn't know anything. Like really, what was wrong with me? If perhaps P1 was reasonable if you thought ever question very well, and deduced some nitty-gritty stuff here and there, expecting you to do that in 45 minutes is ludicrous. P2 was bad. Like I felt you could throw at me anything from topic 7 (particles) and I would solve it, and then the reaction showed you more binding energy, yet a smaller mass? Like TF was that? The waves question was quite ok too. You could deduce the period easily by looking at the graph. It was displaced 3/4 of a period to the right, so if you got that time you simply had to multiply it by 3/4 and you got the period and thus the velocity, RIGHT? The sun albedo questions were perhaps the only questions that were entirely appropriate for the paper. In fact, they were literally the examples that you find in the 6th edition Tsokos. If I just had had the time to study everything, but my teacher barely covered up to chapter 5.1 of the syllabus, and left us on our own 100% to do everything else. Everything else didn't make justice to what I studied, specially the Ice-spring question was obscene. I ANSWERED 19 marks, and assuming that hals of that is correct, we are looking at some 10/50. Pretty difficult, I answered 24 marks. Too many questions for 1hr15min, so unfair we didn't get to choose as we could in past papers. Reply Link to post Share on other sites More sharing options...
Antonio Marco Colangelo Posted May 9, 2016 Report Share Posted May 9, 2016 On 8 May 2016 at 6:07 PM, ibstudent081099 said: Because for the question on the percentage uncertainty I chose the answer with pi because multiplying by the volume that is what I got. If anyone could tell me whether this is wrong I would really appreciate it (I wouldn't like to repeat the mistake tomorrow). Thanks pi doesn't have an uncertainty because its a constant rather than a variable. Reply Link to post Share on other sites More sharing options...
rakinator Posted May 9, 2016 Report Share Posted May 9, 2016 1 hour ago, Antonio Marco Colangelo said: pi doesn't have an uncertainty because its a constant rather than a variable. True but my logic was that because the percentage uncertainty is the uncertainty divided by volume, pi would be somewhere in the expression. 1 Reply Link to post Share on other sites More sharing options...
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