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The Physics PHYA2 thread! 5th June 2013 Watch

  • View Poll Results: What mark do you think you got out of 70?
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    Was wondering, does anyone had the answers to the Examnation-style questions right at the back of the 'AQA Physics AS level' book by Nelson Thornes? P.210 I think. Thanks!
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    (Original post by Raimonduo)
    Was wondering, does anyone had the answers to the Examnation-style questions right at the back of the 'AQA Physics AS level' book by Nelson Thornes? P.210 I think. Thanks!
    https://docs.google.com/file/d/0B7-N...Y28/edit?pli=1
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    mmm, not what I was looking for, but thanks anyway
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    do you guys think we'd lose marks if we don't put our answers in SI units?

    for example on question 4ci in the jan 2013 paper, I put 500,000N, but the mark scheme had the answer as 5*10^5, both are the same, but do you reckon I'd lose the answer mark?
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    hey wtf is up with question 4c iv) in jan 2013?

    they rounded the answer wrong in the mark scheme

    the answer is 1.65*10^4

    but instead of rounding to 1.7*10^4, they rounded it instead to 1.6*10^4

    I'm pretty sure you round up for numbers 5 and over....
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    (Original post by Raimonduo)
    mmm, not what I was looking for, but thanks anyway
    yeh i realised !! loool i'll look for it dw
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    (Original post by Jack93o)
    do you guys think we'd lose marks if we don't put our answers in SI units?

    for example on question 4ci in the jan 2013 paper, I put 500,000N, but the mark scheme had the answer as 5*10^5, both are the same, but do you reckon I'd lose the answer mark?
    Unless the question stated that you must put it in an appropriate amount of significant figures, I think 500,000 is fine. I'll have a look at what I did on Jan13.
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    (Original post by Jack93o)
    hey wtf is up with question 4c iv) in jan 2013?

    they rounded the answer wrong in the mark scheme

    the answer is 1.65*10^4

    but instead of rounding to 1.7*10^4, they rounded it instead to 1.6*10^4

    I'm pretty sure you round up for numbers 5 and over....
    you would get the mark, as long as the step before you showed the full answer at least as  1.65\times10^4 and showed that you rounded to 2 s.f. you would get the mark
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    (Original post by posthumus)
    Just what I was looking for myself, brilliant.... thanks !
    np
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    oh thats alright then for SI units

    btw for question 7e in jan 2013, do you guys know why the mark scheme put so much emphasis on 'even number of multiples of new wavelength'?

    the only requirement for an in-phase relationship between two waves, is that theres a whole number of wavelength difference between them, it doesn't have to be an even number, right?

    also, for 7c, I thought it was a minimum, I see the two waves are in phase, but the detector is at the point where the the two waves are both in equilibrium. If the detector was placed a bit to the left, then I get that it would be a maximum, but where its shown in the diagram, its a minimum surely
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    (Original post by Jack93o)
    oh thats alright then for SI units

    btw for question 7e in jan 2013, do you guys know why the mark scheme put so much emphasis on 'even number of multiples of new wavelength'?

    the only requirement for an in-phase relationship between two waves, is that theres a whole number of wavelength difference between them, it doesn't have to be an even number, right?

    also, for 7c, I thought it was a minimum, I see the two waves are in phase, but the detector is at the point where the the two waves are both in equilibrium. If the detector was placed a bit to the left, then I get that it would be a maximum, but where its shown in the diagram, its a minimum surely
    For 7c, I initially thought that a minimum would be generated as well, because, as you've said, they both reach their equilibrium point at the point they reach the dector (displacement of both waves = 0 at the detector).

    However, upon looking at it closer, I realised that, actually, the wave on the left being received must travel a longer distance, than the wave on the right. So through actually counting the amount of peaks and troughs in both the waves being received, I saw that there were 6 whole wave periods on the wave on the left, and 5 whole wave periods on the wave on the right. Which meant that, considering path difference, if the path difference is a whole integer number of λ, a maximum would occur. Which, in this case, the path difference was 1λ, which meant a maximum would be detected.
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    (Original post by Raimonduo)
    For 7c, I initially thought that a minimum would be generated as well, because, as you've said, they both reach their equilibrium point at the point they reach the dector (displacement of both waves = 0 at the detector).

    However, upon looking at it closer, I realised that, actually, the wave on the left being received must travel a longer distance, than the wave on the right. So through actually counting the amount of peaks and troughs in both the waves being received, I saw that there were 6 whole wave periods on the wave on the left, and 5 whole wave periods on the wave on the right. Which meant that, considering path difference, if the path difference is a whole integer number of λ, a maximum would occur. Which, in this case, the path difference was 1λ, which meant a maximum would be detected.
    For jan 13 7e, can you explain the answer? it's a bit confusing.
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    (Original post by NedStark)
    For jan 13 7e, can you explain the answer? it's a bit confusing.
    Mmm, not too sure about that dude, I got that wrong as well. But I wouldn't worry about it, since it came up in Jan13, it's unlikely that it'll come up tomorrow.
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    [QUOTE=Raimonduo;42958534]Was wondering, does anyone had the answers to the Examnation-style questions right at the back of the 'AQA Physics AS level' book by Nelson Thornes? P.210 I think. Thanks![/

    https://college.esher.ac.uk/subjects..._questions.pdf
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    [QUOTE=acsecnarf;42960187]
    (Original post by Raimonduo)
    Was wondering, does anyone had the answers to the Examnation-style questions right at the back of the 'AQA Physics AS level' book by Nelson Thornes? P.210 I think. Thanks![/

    https://college.esher.ac.uk/subjects..._questions.pdf
    Looks like I need a password for that link.
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    [QUOTE=Raimonduo;42960232]
    (Original post by acsecnarf)

    Looks like I need a password for that link.
    Ah sorry i'll try again
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    (Original post by Raimonduo)
    Was wondering, does anyone had the answers to the Examnation-style questions right at the back of the 'AQA Physics AS level' book by Nelson Thornes? P.210 I think. Thanks!
    Is this what you're looking for?
    Attached Images
  1. File Type: pdf Unit_2_End_of_unit_answes_to_examination_style_questions.pdf (352.4 KB, 58 views)
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    (Original post by h94k)
    Is this what you're looking for?
    YES!!! Thanks a bunch!
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    Could somebody help explain how to answer this question for me please because I don't really understand how you calculate the answer. It is from the Nelson Thornes AS physics textbook and is on page 107, question 4:

    A small toy of weight 2.8N is suspended from a horizontal beam by means of two cords that are attached to the same point on the toy. One cord makes an angle of 60' to the beam and the other cord makes an angle of 40' to the vertical. Calculate the tension in each cord.

    Apparently the cord at 40' has a tension of 1.5 and the other cord has a tension of 1.9, I've tried many ways to work back from the answer but I can just not seem to figure it out :/.
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    (Original post by Jack93o)
    do you guys think we'd lose marks if we don't put our answers in SI units?

    for example on question 4ci in the jan 2013 paper, I put 500,000N, but the mark scheme had the answer as 5*10^5, both are the same, but do you reckon I'd lose the answer mark?
    you would lose a mark so stick to 2 or 3 SF
 
 
 
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