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

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    (Original post by Disney0702)
    Can someone please explain Q1(b)(iii) from Jun '12 Section B.

    I do not understand the second step in the mark scheme.

    Thank you in advance.
    Uploaded a solution to that a few days ago. Here's the link:

    http://www.thestudentroom.co.uk/show...=#post56336639

    Let me know if you need any help/can't read my messy handwriting
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    (Original post by _Caz_)
    We have the same calculators haha Ngl though, I hate my graphics one, only use it in further maths when I have to. It takes like three buttons to delete one line of working! (also it scares me with how much it can do)

    The casio fx-911ES plus is great though!
    Lol yeah, and it has a backlight! For when you're furiously calculating at night
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    Name:  ImageUploadedByStudent Room1433775757.244349.jpg
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    Can someone give me a hint on what to do please


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    (Original post by Protoxylic)
    Lol yeah, and it has a backlight! For when you're furiously calculating at night
    casio knows we maths people too well :'D
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    (Original post by gcsestuff)
    Name:  ImageUploadedByStudent Room1433775757.244349.jpg
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Size:  36.5 KBCan someone give me a hint on what to do pleasePosted from TSR Mobile
    This happens when they are first at a 2pi phase difference. The faster one (P) will therefore have done one more complete oscillation than the slower one (Q), so if we assume Q has done n complete oscillations we have 1.9(n+1)=1.95n or 1.9=0.05n, i.e. Q does n=38 oscillations.
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    3000+ posts! You guys really do love physics


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    (Original post by gcsestuff)
    Name:  ImageUploadedByStudent Room1433775757.244349.jpg
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    Can someone give me a hint on what to do please


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    I struggle with these questions too. There is a way of doing them though and I don't understand it but it works.

    find the difference between the two time periods.

    If it wants the number of oscillations of the one with the longer time period, divide the value of the shorter time period by the difference between the two time periods.

    If it wants the number of oscillations of the one with the shorter time period, divide the value of the longer time period by the difference between the two time periods.

    I know this wasn't exactly what you were looking for and I really struggle to get my head around these too but that method works every time
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    (Original post by tawaz1997)
    The top one is 'B'.Electromagnetic induction only happens, in this case, when the magnitude or direction of flux changes. When the current is increasing, there's em induction going on, when its constant nothing happens,

    Sorry I'm bad at explaining...haha

    The other one...come on, that's pretty straight forward
    GMm/r^2 = mv^2/r where M is the mass of the sun and m the mass of the earth,r is the distance, = radius of earth + orbital radius + radius of the sun

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    I think you're very wrong for the first one and I definitely think it is 'C'. My reasoning is that if you go to a maximum value of current then switch it off, then that will be the greatest change in the coil X's magnetic field produced since it goes to a maxima to nothing. Therefore, the other coil will cut the coil 'X' field lines at the fastest rate for this event out of all the other events listed and hence that will induce highest emf for other coil and thus highest reading on the ammeter.
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    (Original post by _Caz_)
    I struggle with these questions too. There is a way of doing them though and I don't understand it but it works.

    find the difference between the two time periods.

    If it wants the number of oscillations of the one with the longer time period, divide the value of the shorter time period by the difference between the two time periods.

    If it wants the number of oscillations of the one with the shorter time period, divide the value of the longer time period by the difference between the two time periods.

    I know this wasn't exactly what you were looking for and I really struggle to get my head around these too but that method works every time
    Mate that's perfect thanks! Hope it comes up now!!!


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    (Original post by adil1231)
    I think you're very wrong for the first one and I definitely think it is 'C'. My reasoning is that if you go to a maximum value of current then switch it off, then that will be the greatest change in the coil X's magnetic field produced since it goes to a maxima to nothing. Therefore, the other coil will cut the coil 'X' field lines at the fastest rate for this event out of all the other events listed and hence that will induce highest emf for other coil and thus highest reading on the ammeter.
    Yeah that's true.


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    Cd did you ask your teacher about the gravity question regarding orbits?


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    Everyone's saying the biology unit 4 paper contained all unit 1 and 2 questions. I hope that won't happen to us, but then I guess that's what's gonna happen over the coming years with one paper sat at the very end


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    (Original post by _Caz_)
    I struggle with these questions too. There is a way of doing them though and I don't understand it but it works.

    find the difference between the two time periods.

    If it wants the number of oscillations of the one with the longer time period, divide the value of the shorter time period by the difference between the two time periods.

    If it wants the number of oscillations of the one with the shorter time period, divide the value of the longer time period by the difference between the two time periods.

    I know this wasn't exactly what you were looking for and I really struggle to get my head around these too but that method works every time
    There was a difference of 0.1, beween T1 = 2 and T2 = 1.9, but the answer was 38 not 19, whY?
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    (Original post by gcsestuff)
    Cd did you ask your teacher about the gravity question regarding orbits?


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    Yeah only just got a reply today!

    "Radius" means use that figure. "Height" means add the radius to the distance given.



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    (Original post by AR_95)
    There was a difference of 0.1, beween T1 = 2 and T2 = 1.9, but the answer was 38 not 19, whY?
    2 doesn't go into 19, so it must be doubled
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    Does anyone have any notes specifically for the wordy, 6 mark questions? Any help is much appreciated lol
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    (Original post by adil1231)
    I think you're very wrong for the first one and I definitely think it is 'C'. My reasoning is that if you go to a maximum value of current then switch it off, then that will be the greatest change in the coil X's magnetic field produced since it goes to a maxima to nothing. Therefore, the other coil will cut the coil 'X' field lines at the fastest rate for this event out of all the other events listed and hence that will induce highest emf for other coil and thus highest reading on the ammeter.
    Yeah, actually you're right. But man you can't be going around telling people they are 'very wrong', the exam is in 3 days and my confidence has just gone from 100 to 0...haha
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    (Original post by gcsestuff)
    Everyone's saying the biology unit 4 paper contained all unit 1 and 2 questions. I hope that won't happen to us, but then I guess that's what's gonna happen over the coming years with one paper sat at the very end


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    Biology do have a very big emphasis on continuing to know unit 1/2 stuff I think though! While unit 4 of physics must contain some content from last year, it's usually in a simple way for 1-2 marks and often on the data sheet (eg. knowing that power loss due to resistance is proportional to current squared - P = I2R is an AS formula).
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    (Original post by CD223)
    Yeah only just got a reply today!

    "Radius" means use that figure. "Height" means add the radius to the distance given.



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    That's good thanks man!!


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    (Original post by _Caz_)
    Uploaded a solution to that a few days ago. Here's the link:

    http://www.thestudentroom.co.uk/show...=#post56336639

    Let me know if you need any help/can't read my messy handwriting
    Ah thank you very much

    I have just one question.

    Does impulse of an object have weight?
    I'm inferring this from the second step in your solutio.
 
 
 
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