Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie

**HL Maths P2 Before/After

11516171820

Comments

  • Registered Users, Registered Users 2 Posts: 1,763 ✭✭✭finality


    oh sorry. for that i said that alpha>beta a small change will see a larger effect in beta and when beta>alpha a small change will see a larger effect in alpha. not too sure on that though

    I said that too. I was in such an emotional state by that stage though that I was just trying to write down ANYTHING for the sake of maybe getting attempt marks or something. Haha.


  • Registered Users Posts: 789 ✭✭✭FaoiSin


    The only questions I got right were 2,4,Half of 5, Quarter of 6 and maybe all of 7. 8 was basically a different language. Now ye can all feel good about yerselves :D


  • Registered Users Posts: 217 ✭✭RedTexan


    Nazata wrote: »
    It's cool.
    Yeah, more or less everyone I've talked to in my school said they just said a statement so I'm curious to see if anyone else got the same answer...
    I got that as well, made a triangle when the distance between the point and the origin and the point and the crook of the arm were equal and that would mean a change in alpha would cause the same as the change in beta so anything under this would make the change in beta more significant, came out at 33.55 or something I think.


  • Registered Users Posts: 134 ✭✭Spattersonox


    I just guessed beta. maybe I'll get 3 marks for that as my reasoning was a complete guess!


  • Registered Users Posts: 142 ✭✭Nazata


    RedTexan wrote: »
    I got that as well, made a triangle when the distance between the point and the origin and the point and the crook of the arm were equal and that would mean a change in alpha would cause the same as the change in beta so anything under this would make the change in beta more significant, came out at 33.55 or something I think.

    Perfect, I definitely around 33.6 :)


  • Advertisement
  • Registered Users Posts: 176 ✭✭sdiff


    oh sorry. for that i said that alpha>beta a small change will see a larger effect in beta and when beta>alpha a small change will see a larger effect in alpha. not too sure on that though

    The clue was in the question when it said the change in distance ~ arc length.

    Arc length is equal to change in angle (in radians) multiplied by radius. Since change in angle was constant, the only relevant one was radius. The radius is basically this distance from P or Q to R.

    I think alpha was the one at P so therefore a change in alpha will result in a change in arc length that is proportional to PR (R being the end location/the one with which we are trying to find the error of). Q was the one at beta so if beta changes by one, the change in arc length is proportional to QR. Therefore, for the first question, a change in alpha is more important. More generally (for the second question), alpha is more important when PR > QR, and beta more important when QR>PR.

    Did anybody else get this?


  • Registered Users Posts: 120 ✭✭That Handsome Devil


    sdiff wrote: »
    The clue was in the question when it said the change in distance ~ arc length.

    Arc length is equal to change in angle (in radians) multiplied by radius. Since change in angle was constant, the only relevant one was radius. The radius is basically this distance from P or Q to R.

    I think alpha was the one at P so therefore a change in alpha will result in a change in arc length that is proportional to PR (R being the end location/the one with which we are trying to find the error of). Q was the one at beta so if beta changes by one, the change in arc length is proportional to QR. Therefore, for the first question, a change in alpha is more important. More generally (for the second question), alpha is more important when PR > QR, and beta more important when QR>PR.

    Did anybody else get this?

    Yup, although I went further and gave it as if cosine Beta is greater or smaller than a certain value which I forget now


  • Registered Users Posts: 142 ✭✭Nazata


    sdiff wrote: »
    I think alpha was the one at P so therefore a change in alpha will result in a change in arc length that is proportional to PR (R being the end location/the one with which we are trying to find the error of). Q was the one at beta so if beta changes by one, the change in arc length is proportional to QR. Therefore, for the first question, a change in alpha is more important. More generally (for the second question), alpha is more important when PR > QR, and beta more important when QR>PR.

    Did anybody else get this?

    Yeah, that's what I got, then worked out the conditions when QR is greater than PR. All of the above seems correct..


  • Registered Users Posts: 176 ✭✭sdiff


    Nazata wrote: »
    Yeah, that's what I got, then worked out the conditions when QR is greater than PR. All of the above seems correct..

    Aha, so you worked out the angles too... I didn't bother with that, hope it won't be necessary.


  • Registered Users, Registered Users 2 Posts: 8,671 ✭✭✭GarIT


    sdiff wrote: »
    Aha, so you worked out the angles too... I didn't bother with that, hope it won't be necessary.

    The question asked which will move more, it didn't ask for any speific method. You should get full marks for whatever explination, other than that displacement being greater the further the object is from the axis of rotation is a proven mathmatical and sceintifical fact, you should be able to just state it without proving it for full marks. I just said change in R is greater in PR when PR is greater than QR and then the opposite as well.


  • Advertisement
  • Registered Users Posts: 142 ✭✭Nazata


    GarIT wrote: »
    The question asked which will move more, it didn't ask for any speific method. You should get full marks for whatever explination, other than that displacement being greater the further the object is from the axis of rotation is a proven mathmatical and sceintifical fact, you should be able to just state it without proving it for full marks. I just said change in R is greater in PR when PR is greater than QR and then the opposite as well.

    In part (c) they did however ask for the conditions where a small change in beta will have more effect than a small change in alpha:

    The answer to part (b) above depends on the particular position of the arm. That is, in certain
    positions, the location of R is more sensitive to small errors in α than to small errors in β,
    while in other positions, the reverse is true. Describe, with justification, the conditions under
    which each of these two situations arises.

    I agree with you that he'll either get full marks or close to it...


  • Registered Users Posts: 6 Megamoo


    Im from a pilot school and if paper 2 was recieved as hard ye should have seen or paper 1


  • Registered Users, Registered Users 2 Posts: 8,572 ✭✭✭Canard


    I was really disappointed in Maths PII... The only people in my year who got Q8 out do physchem. :mad: F*cking disgraceful, it was physics tbh, I'd seen nothing of the sort ever (and that stupid parallelogram thing too...) so I was being tested on things i'd never seen. And direction of causality?! Ffs.

    Just glad I dont need to pass but I probably did.


  • Registered Users Posts: 217 ✭✭RedTexan


    Patchy~ wrote: »
    I was really disappointed in Maths PII... The only people in my year who got Q8 out do physchem. :mad: F*cking disgraceful, it was physics tbh, I'd seen nothing of the sort ever (and that stupid parallelogram thing too...) so I was being tested on things i'd never seen. And direction of causality?! Ffs.

    Just glad I dont need to pass but I probably did.
    I do both physics, chemistry and applied maths and to be honest I don't think that they helped me at all in that exam or that question, although I do think I got it right. To be honest the final part was nothing like anything I'd ever seen, anywhere


  • Registered Users, Registered Users 2 Posts: 8,572 ✭✭✭Canard


    I just drew semicircles trying to imagine how they might rotate...but hey, I never planned to get a single mark there anyway. :o


  • Registered Users, Registered Users 2 Posts: 8,671 ✭✭✭GarIT


    Patchy~ wrote: »
    I was really disappointed in Maths PII... The only people in my year who got Q8 out do physchem. :mad: F*cking disgraceful, it was physics tbh, I'd seen nothing of the sort ever (and that stupid parallelogram thing too...) so I was being tested on things i'd never seen. And direction of causality?! Ffs.

    Just glad I dont need to pass but I probably did.

    Its nothing like physics at all. Its aimed at people with an aptitude for problem solving. Am I the only person who thought the direction of causility was so obvious? Anyone know what the proper answer was?


  • Registered Users, Registered Users 2 Posts: 8,671 ✭✭✭GarIT


    Patchy~ wrote: »
    I was really disappointed in Maths PII... The only people in my year who got Q8 out do physchem. :mad: F*cking disgraceful, it was physics tbh, I'd seen nothing of the sort ever (and that stupid parallelogram thing too...) so I was being tested on things i'd never seen. And direction of causality?! Ffs.

    Just glad I dont need to pass but I probably did.

    Its nothing like physics at all. Its aimed at people with an aptitude for problem solving. Am I the only person who thought the direction of causility was so obvious? Anyone know what the proper answer was?


  • Closed Accounts Posts: 1,778 ✭✭✭leaveiton


    GarIT wrote: »
    Its nothing like physics at all. Its aimed at people with an aptitude for problem solving. Am I the only person who thought the direction of causility was so obvious? Anyone know what the proper answer was?

    I don't actually know what the physics course is like but I thought the question would have suited someone better with a mind for things like motion and mechanics. I personally love problem solving and I'm usually good at the 3d problems involving pyramids and the like, but my mind just does not understand mechanics at all.


  • Registered Users, Registered Users 2 Posts: 8,572 ✭✭✭Canard


    GarIT wrote: »
    Its nothing like physics at all. Its aimed at people with an aptitude for problem solving. Am I the only person who thought the direction of causility was so obvious? Anyone know what the proper answer was?
    My friend's dad did physics and said the angle thing was a basic physics concept. It was definitely not straightforward trig and it wasnt a problem soluble with any of the trig we bloody did.

    I took a guess at it and said it was a NE direction and the direction could be reversed by reducing tax and that was the importance. Anyone could make an educated guess but it wasnt on the course, thats the problem! Even Brendan Guildea didnt know what it was and I couldnt find an answer on google.


  • Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    GarIT wrote: »
    Its nothing like physics at all. Its aimed at people with an aptitude for problem solving. Am I the only person who thought the direction of causility was so obvious? Anyone know what the proper answer was?


    I wasn't annoyed with the direction of causality... I was expecting something theory wise none of saw before so I just blathered on and on and on....

    I would've got 8 right if I read the question right! :/ For the last part I thought it said the set of co-ordinates for the whole arm. I even wrote out the equation of the circle which would encompass the semicircles... I was ragin when I realised! I'll probably lose my A1 over that q8 through silly mistakes and calculation errors... :/ I'm just hoping they'll be extremely extremely generous in their marking! :(:o


  • Advertisement
  • Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    leaveiton wrote: »
    I don't actually know what the physics course is like but I thought the question would have suited someone better with a mind for things like motion and mechanics. I personally love problem solving and I'm usually good at the 3d problems involving pyramids and the like, but my mind just does not understand mechanics at all.


    I'm the same! In my apptitude test things (I think they're the DATS) I got like 99 in Maths and like 80 in mechanics... :/ If it was a "proper" question It would have been a lovely exam... ;/


  • Registered Users Posts: 789 ✭✭✭FaoiSin


    Patchy it clearly states in the syllabus that you must be able to: "Solve angles with Robot Arm thingys". Read it carefully next time! :P


  • Closed Accounts Posts: 1,778 ✭✭✭leaveiton


    ChemHickey wrote: »
    I'm the same! In my apptitude test things (I think they're the DATS) I got like 99 in Maths and like 80 in mechanics... :/ If it was a "proper" question It would have been a lovely exam... ;/

    Yep I was the same, got 90 - 99 in pretty much everything bar mechanics which I think I got 75 or so in. I remember my guidance counsellor saying "These are great results, you've an aptitude for nearly anything... but maybe stay away from physics" :P I wouldn't have really minded had we been given fair warning about that type of question, but noooo! And I think it was finality that said in another thread, it would have also been fine had the question not been worth so much. I think I got about 6/8 questions mostly right in that exam, but because I messed up q8, that's 75 marks gone immediately!


  • Registered Users Posts: 176 ✭✭sdiff


    GarIT wrote: »
    Its nothing like physics at all. Its aimed at people with an aptitude for problem solving. Am I the only person who thought the direction of causility was so obvious? Anyone know what the proper answer was?

    I also had never heard of the phrase but found it relatively easy to deduce what it meant. What did you get? I just said it was describing which variable caused which - was the higher interest rates causing higher arrears or vice versa. Google seems to have vindicated this answer. :p


  • Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    leaveiton wrote: »
    Yep I was the same, got 90 - 99 in pretty much everything bar mechanics which I think I got 75 or so in. I remember my guidance counsellor saying "These are great results, you've an aptitude for nearly anything... but maybe stay away from physics" :P I wouldn't have really minded had we been given fair warning about that type of question, but noooo! And I think it was finality that said in another thread, it would have also been fine had the question not been worth so much. I think I got about 6/8 questions mostly right in that exam, but because I messed up q8, that's 75 marks gone immediately!

    If it was a 25marker I wouldn't really care at all as there is a tolerance of 60marks for A1/A2 border, but 75marks.... I am just hoping they give almost everyone "high-partial-credit" for it all.

    I just wished there was a 75marker for probablilty... that shtuff is my thing.. :cool: or even a second Paper1! :L

    I'd happily resit P2 tomorrow if they'd let me!


  • Closed Accounts Posts: 1,778 ✭✭✭leaveiton


    ChemHickey wrote: »
    If it was a 25marker I wouldn't really care at all as there is a tolerance of 60marks for A1/A2 border, but 75marks.... I am just hoping they give almost everyone "high-partial-credit" for it all.

    I just wished there was a 75marker for probablilty... that shtuff is my thing.. :cool: or even a second Paper1! :L

    I'd happily resit P2 tomorrow if they'd let me!

    Exactly, someone was trying to console me by saying "Oh but you got those other questions out" but it's a bit worthless when I didn't get anything in one that was worth a good 12.5% of the whole maths exam! I'm not even aiming for anything around the A/B mark, all I wanted was a C3 and I really doubt I got that :( If it'd been a trig question like the ones in the samples I would have been flying. I just kept feeling in the exam like it was a mock, a really bad quality stupid mock, but it wasn't :(


  • Closed Accounts Posts: 3,479 ✭✭✭ChemHickey


    leaveiton wrote: »
    Exactly, someone was trying to console me by saying "Oh but you got those other questions out" but it's a bit worthless when I didn't get anything in one that was worth a good 12.5% of the whole maths exam! I'm not even aiming for anything around the A/B mark, all I wanted was a C3 and I really doubt I got that :( If it'd been a trig question like the ones in the samples I would have been flying. I just kept feeling in the exam like it was a mock, a really bad quality stupid mock, but it wasn't :(


    I'm sure for even attempting it we'll get like 8% of it, or maybe more *fingers crossed*

    Maths was one of the only subjects I wanted an A in.

    Not to sound bad or anything, I'd rather get an A1 in maths and have gotten B's and C's in the rest to have gotten 7A1'S and an A2 in maths... It's the principle in it.. :/


  • Closed Accounts Posts: 1,778 ✭✭✭leaveiton


    ChemHickey wrote: »
    I'm sure for even attempting it we'll get like 8% of it, or maybe more *fingers crossed*

    Maths was one of the only subjects I wanted an A in.

    Not to sound bad or anything, I'd rather get an A1 in maths and have gotten B's and C's in the rest to have gotten 7A1'S and an A2 in maths... It's the principle in it.. :/

    I really wanted an A in maths back at the beginning of the year. I've always loved maths and got an A in the JC and all that, but I unfortunately just had a hopeless teacher. Would have been so handy for points though!


  • Registered Users, Registered Users 2 Posts: 1,763 ✭✭✭finality


    leaveiton wrote: »
    Yep I was the same, got 90 - 99 in pretty much everything bar mechanics which I think I got 75 or so in. I remember my guidance counsellor saying "These are great results, you've an aptitude for nearly anything... but maybe stay away from physics" :P I wouldn't have really minded had we been given fair warning about that type of question, but noooo! And I think it was finality that said in another thread, it would have also been fine had the question not been worth so much. I think I got about 6/8 questions mostly right in that exam, but because I messed up q8, that's 75 marks gone immediately!

    haha I was the same, I found the mechanics section of the dats much harder than the other sections...though I somehow got 86 in it in the end which isn't bad. :L I got 100% in spelling, proudest moment of my life.

    Applied maths and physics didn't help me with q8 at all, I felt. I'm really good at mechanics questions in physics but I made a total balls of q8. :(
    sdiff wrote: »
    I also had never heard of the phrase but found it relatively easy to deduce what it meant. What did you get? I just said it was describing which variable caused which - was the higher interest rates causing higher arrears or vice versa. Google seems to have vindicated this answer. :p
    That's what I said too. I'd never heard of it but I can't really think of anything else it could've been?


  • Advertisement
  • Registered Users, Registered Users 2 Posts: 1,763 ✭✭✭finality


    ChemHickey wrote: »
    I'm sure for even attempting it we'll get like 8% of it, or maybe more *fingers crossed*

    Maths was one of the only subjects I wanted an A in.

    Not to sound bad or anything, I'd rather get an A1 in maths and have gotten B's and C's in the rest to have gotten 7A1'S and an A2 in maths... It's the principle in it.. :/

    This is exactly how I feel. I'm pretty sure I got a B1, even if I see 7A1's and that B1 on my results sheet I'll be fairly gutted.


Advertisement