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

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    anyone know why when doing ratio multiple choice and this like that you dont take into account the square root??
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    (Original post by Plasmapause)
    Thanks for the reply.
    Just wondering but where did the 0.5 come from? :confused:
    Aeea under the graph.
    Sorry didnt made that clear before.

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    predictions for 6 marker?
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    (Original post by lukebiddell)
    I get it now thanks! Goodluck tomorrow
    and you
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    How do you answer question 25 on this please!

    http://filestore.aqa.org.uk/subjects...1-QP-JUN14.PDF
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    Anyone else here planning on doing Section B first?
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    How do you answer this question?
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    (Original post by Kennethm)
    ive been trying to find out lol

    https://60abffc9b401b1c0936e01291c15...%20Physics.pdf

    Q13, the answer is A meaning you dont make it minus on the other side. Which makes me wonder do you do the same or the opposite if they were positive?
    basically im at the stage at:
    either:
    1) 480-4x = -16x
    2/ 480 - 4x = 16x

    for 1 the answer would be negative 20 positive (right one i think)

    I have had an idea maybe because potential is scalar you can ignore negative? (seems like an excuse tho )
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    (Original post by SuperMushroom)
    How do you answer question 25 on this please!

    http://filestore.aqa.org.uk/subjects...1-QP-JUN14.PDF
    Primary power= 0.26*230 = 59.8W

    Secondary voltage:

    As Ns/Np = Vs/Vp,
    Vs = Vp * turns ratio
    = 230 * 500/1150
    = 100V

    Secondary power= 100V*0.5A= 50W

    50/59.8 * 100 = 83.6% so C
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    (Original post by dominicwild)
    How do you answer this question?
    is the answer A?
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    (Original post by oonic0rn)
    http://filestore.aqa.org.uk/subjects...1-QP-JAN13.PDF -

    could someone please explain number 9 and 10 please
    9) The phase difference between P and Q is 0.05s, it takes Q 38 oscillations to move in phase with P as with every oscillation it is doing is 0.05s slower. 1.9/0.05 =38.

    10) The forces between M1 and the small mass is equal to the force between M2 and the small mass. If you call the small mass m, GM1m/r1^2 =GM2m/r2^2 , the m will cancel, then you rearrange to get answer C.
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    (Original post by HenryHein)
    Primary power= 0.26*230 = 59.8W

    Secondary voltage:

    As Ns/Np = Vs/Vp,
    Vs = Vp * turns ratio
    = 230 * 500/1150
    = 100V

    Secondary power= 100V*0.5A= 50W

    50/59.8 * 100 = 83.6% so C
    Thanks mate!
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    (Original post by a.a.k)
    Ft=mv

    So v =Ft/m

    (0.5*10*40)/0.25=800

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    I have seen you on another thread cant remember which one :P
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    Predictions on how grade boundaries will go? June 14 was a fairly tough paper and grade boundaries were highest ever, so I'm a bit scared since I need an a* in this :/
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    6 MARKER : Potato set into hard harmonic motion and describing the damping effects
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    (Original post by Kennethm)
    ive been trying to find out lol

    https://60abffc9b401b1c0936e01291c15...%20Physics.pdf

    Q13, the answer is A meaning you dont make it minus on the other side. Which makes me wonder do you do the same or the opposite if they were positive?
    You use V=Q/(4pie0r) here sign is very important use 4*10^-6 and -16*10^-6 in that formula and potential adds as there is no direction since 16*10^-6 is 4 times greater than 4*10^-6 then for them to cancel and make zero the distance from the point of zero potential from the -16*10^-6 charge must be 4 times greater than the distance of the point from the 4*10^-6 charge so the point lies 1/5 of 120mm from A which equals 24mm.If you sub in this value into both and add then the potential will be zero.
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    (Original post by Deddy)
    9) The phase difference between P and Q is 0.05s, it takes Q 38 oscillations to move in phase with P as with every oscillation it is doing is 0.05s slower. 1.9/0.05 =38.

    10) The forces between M1 and the small mass is equal to the force between M2 and the small mass. If you call the small mass m, GM1m/r1^2 =GM2m/r2^2 , the m will cancel, then you rearrange to get answer C.
    thankyou so much!! any chance you could go through question 17 as well?
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    Guys whos gonna do Section B fist then A? I think that way can be safer (if you run out of time guess MC)
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    (Original post by Leonacatherine)
    Can anyone explain ehat they mean by E in the june 14 six marker
    I get the rest but dont get wat theyre referring to by E
    http://filestore.aqa.org.uk/subjects...W-MS-JUN14.PDF
    http://filestore.aqa.org.uk/subjects...2-QP-JUN14.PDF
    emf of the battery. Basically the voltages through the resistor and the capacitor keep changing but at any moment they add up to the emf.
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    Those worried about timing, just do section A first within 45 minutes. If you run over, go on to section B and come back at the end to guess.


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