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AQA Physics PHYA4 - 20th June 2016 [Exam Discussion Thread] watch

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    (Original post by Yo12345)
    Amplitude must be small


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    I said the angle between the equilibrium position of the string at rest and the the position of the line at the amplitude must be 10 degrees when I measured out when to drop the ball. Sounds acceptable?
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    (Original post by ombtom)
    Instead of using v and V I'll use v = 2, V = -1 for the velocities.

    Everyone's saying mv - VN = 0
    So V = mv/N
    -1 = 2m/N

    Since m/N > 0, this implies that -1 = 2 x positive constant.

    What's going on?
    If V=-1 the formula would be mv+VN=0. However, considering right to be positive mv-VN=0 is the correct momentum conservation.
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    To be honest it will probably end up with them accepting both positive and negative due to all the confusion.
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    How many marks was the radius calculation? Was it worth 2 or 3?
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    (Original post by marioman)
    In your dreams.
    If only... I think more like 57 for an A* if we're lucky. 62 or 63 for 120 UMS depending on standard deviation.

    And I think that's me being conservative.
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    (Original post by 1017bsquad)
    Ok i got scared for a moment xD, I didn't do well on this paper :/ couldnt even answer the time constant question... and the kinetic energy fml
    Yeah the E_alpha derivation got me too. I only managed to get to something like:

    E_alpha = E(1 - ((1/2N)m^2v^2)/E)

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    Does anyone have an unofficial markscheme?
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    (Original post by English-help)
    Thanks you! I need 85+ in Unit 5 now which will be hard but i'll have to get it for my offer! :/
    Best of luck to you! What is your offer for, which grades and where?
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    All these multiple choice answers with many D's, I don't really think its right. I barely had D's...
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    (Original post by -Gifted-)
    Defo 2F and X to Y.
    if they are both positive, then the force on X has direction Y to X (repulsive).
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    (Original post by js.int)
    Yeah the E_alpha derivation got me too. I only managed to get to something like:

    E_alpha = E(1 - ((1/2N)m^2v^2)/E)

    Yeah, that was the one question where I just couldn't see how to get to it.

    Everything else was either a case of "Oh I know this" or "Ahhh I wish I revised this more" but.. this one.. I just couldn't recall anything about it at all and I couldn't derive the right equation
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    What was the momentum of the alpha particle ? 8.6x10^-19???
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    (Original post by Sid1234)
    if they are both positive, then the force on X has direction Y to X (repulsive).
    Initially it was negative and was y to x. after, the potential was positive, so must have changed direction .
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    (Original post by Tokhmehsag)
    What was the momentum of the alpha particle ? 8.6x10^-19???

    I got like 2*10^-20
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    (Original post by -Gifted-)
    All these multiple choice answers with many D's, I don't really think its right. I barely had D's...
    Just so you know, for the past 10 past papers, there has always been an even distribution of answers A, B, C and D. In every paper so far, there's been 6 answers for 3 letters and then 7 answers for 1 letter.
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    (Original post by Tokhmehsag)
    What was the momentum of the alpha particle ? 8.6x10^-19???
    I got 1.6*19^-19 or something like that
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    (Original post by Sid1234)
    if they are both positive, then the force on X has direction Y to X (repulsive).
    Yeah agree
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    (Original post by tanyapotter)
    How many marks was the radius calculation? Was it worth 2 or 3?
    The radius of Venus question was worth 3 marks
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    (Original post by Tokhmehsag)
    What was the momentum of the alpha particle ? 8.6x10^-19???
    Nope, missed factor at the end (I got this and corrected)
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    (Original post by Random1357)
    Nope, missed factor at the end (I got this and corrected)
    What did you end up getting? A fair few in my college on one or two said 1.15x10^-19 (I think it was ^-19 anyway)
 
 
 
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