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AQA Physics PHYA4 - Thursday 11th June 2015 [Exam Discussion Thread] Watch

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    (Original post by Kingnig)
    Does anyone has a list of past grade boundaries?
    See the first post
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    (Original post by saad97)
    Could you explain how the get the right answer please? Ican't seem to get it.
    Also these types of questions are on every paper, is there a specific way to do them because I always get them wrong
    Sorry, I missed out the squares for the distances. You should end up with
    0.5/d^2 =1/(20x10-3)^2 , then d=14mm.

    I think that the best approach is to look at what they give you and think, if the Force is F at one point, and 0.5F at another, then they are multiples of eachother so you can equate them.

    Another question I saw like this was when they told you that gravitational potential at one point was 45V and another was 50V, again same approach the 45 is 0.9(50).
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    (Original post by huniibehi)
    This is the hardest momentum question I've seen, any ideas??

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    Mass is 0.5kg.

    The acceleration on the moon is 10/6, hence its velocity will change by 30/6 from 3 seconds of falling = 5 metres/second.

    Momentum = mv = 0.5*5 = 2.5?
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    Wow some of these questions have got me feeling like Sterling with a 1v1 against de gea
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    (Original post by Lau14)
    See the first post
    Oops, the nerves are already kicking in XD
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    (Original post by utvctang)
    What's confusing is that i thought Emf and flux linkage were proportional (Faraday's law) - but the equations show that flux linkage uses cos, while emf uses sign, which means they reach a maximum value and minimum value at different angles?
    Yeah that's exactly right but EMF is not proportional to flux linkage, it is proportional to the RATE OF CHANGE of flux linkage so the maxima and minima of flux linkage happen when the normal to the coil is parallel to the field lines and the maxima and minima of EMF happen when the normal is perpendicular to the field lines.
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    (Original post by Kingnig)
    Oops, the nerves are already kicking in XD
    Happens to all of us! Just got to stay calm in the exam
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    (Original post by huniibehi)
    This is the hardest momentum question I've seen, any ideas??

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    the velocity after falling for 3 seconds: use v=u+at
    where a = g/6

    mass = mg

    momentum = mass * velocity
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    (Original post by _Caz_)
    Right okay, the formula for emf is BANwsin(wt). Sin functions vary between -1 and 1 so max emf will be when sin(wt)=1. Max emf=BANw. As you know, Flux linkage is BAN. So if you make BAN the subject of the formula you get maxemf/w=flux linkage (BAN) . From circular motion you know that w=2*pi*f so you substitute w with that and it gives you A
    Clever. Thanks a lot!
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    Emf=Blv
    Emf=emf zero*sin( 2*pi*f*t)

    These are not in the data sheet.

    Anyother plz share

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    (Original post by oonic0rn)
    when calculating rsultant electric fields, is it E1+E2 if the charges are negative and positive and E1-E2 if the charges are the same?? (like two positives)
    Yes, that's right. It always helps to draw a little diagram though.

    +ve E1 -------------------> charge E2 -----------------> -ve

    +ve E1 ---------------------> charge E2 <--------------------- + ve
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    (Original post by Dante991)
    Wow some of these questions have got me feeling like Sterling with a 1v1 against de gea
    Some have got me feeling like David Moyes' time as Utd manager.


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    If I were to give a guide on 6 markers without even knowing the topic, I'd say:
    1) Bring up relevant keys points, that you know relate directly to the topic.
    2) You can never write too much, write till you know nothing else - the examiner can always extract marks from your text.
    3) Look at the question and try to imagine the mark scheme, what are they looking for?

    Using this helped me loads for unit 1 and 2 6 markers
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    (Original post by CD223)
    Some have got me feeling like David Moyes' time as Utd manager.


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    Some got me feeling like Wenger against Mourinho
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    (Original post by HenryHein)
    Yes, that's right. It always helps to draw a little diagram though.

    +ve E1 -------------------> charge E2 -----------------> -ve

    +ve E1 ---------------------> charge E2 <--------------------- + ve
    ahh yes thankyou!
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    whats the prediction for the 6 marker?
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    http://filestore.aqa.org.uk/subjects...1-QP-JAN13.PDF

    question 12 anyone pleeeeeeeeeease?
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    Just wanna say thanks to everyone for making this such a lively and buzzing thread since the beginning. It's definitely helped me prepare and I hope it has for everyone else!

    Let's all smash this paper!


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    (Original post by fruity97)
    I'm praying they ask about a resonance one like in the specimen paper! How the phase different varies with the driving frequency!
    Anyone think it could be on transformers, energy losses? That hasn't come up in a while, would be a great 6 marker!
    please can you link me the specimen paper?
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    (Original post by CD223)
    Just wanna say thanks to everyone for making this such a lively and buzzing thread since the beginning. It's definitely helped me prepare and I hope it has for everyone else!

    Let's all smash this paper!


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    Goodluck mate, thanks for your help
 
 
 
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