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AQA Physics PHYA5 - Thursday 18th June 2015 [Exam Discussion Thread] Watch

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    (Original post by CD223)
    Cocked up the written paper. Got 24/25 on the MC but messed up the damping question. Also drew the current graph wrong and definitely didn't get 6/6 on the six marker.

    How are you revising for unit 5?


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    That definitely doesn't sound too bad, I'm sure it's still an A* or a high A at least...

    Unit 5: Section A is good. Turning points is also good but you literally need to memorize the mark schemes if you want to get top marks. I think this is what people find so hard (hence low grade boundaries). I only picked it because I find the topics interesting and wanted to learn some basic special relativity.
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    (Original post by PotterPhysics)
    Nope that's the only one.

    There is the one where they derive pV=\frac{1}{3}Nm\overline{c}^2 and another one where they plug in pV=NkT into the left side of this equation and rearrange to get \frac{1}{2}m\overline{c}^2=\frac  {3}{2}kT (kinetic energy of an ideal gas is directly proportional to temperature in K)
    I kinda skipped learning the first one you mentioned.... Hoping only the other one will come up
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    (Original post by Mehrdad jafari)
    Was it for Thomson's observations?


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    I think Thomson's is the fine beam tube one. This one uses a uniform electric field between two plates. 1.3 here should help: https://e301d5e52e4368a053856306f647...20Electron.pdf
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    (Original post by Protoxylic)
    This is the one where you use s=1/2at^2 and VQ/d = ma right? And Yes, you do. It does only say you need to know one, but they can ask you any of of the four that are mentioned
    Yep that's the one and thanks
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    This is my second time I've received notification that a user "examiningboard" has replied on this thread but i don't seem to find him!


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    (Original post by Mehrdad jafari)
    This is my second time I've received notification that a user "examiningboard" has replied on this thread but i don't seem to find him!


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    AQA are checking what we know so they put in questions no one is talking about
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    (Original post by ubisoft)
    AQA are checking what we know so they put in questions no one is talking about
    Let's all talk about things we don't know about then!! And pretend we know and just ask each other questions out of textbooks with the answers in the back! Haha or pretend we don't know about stuff we do! Who knows... One of you could be AQA!
    In all honesty though I'm sure the papers have already been sent and I don't think they could ask us stuff just because we've been talking about it and learning it... Everyone's been doing that for the past two years!
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    Can someone let me know if this is correct please!


    During fission and fusion processes, mass is converted into energy and this energy is released. The released energy is the binding energy, which is equal to the strong nuclear force energy. Since mass is converted into energy, the mass of the reactants > mass of the products.

    For e.g. a neutron is absorbed by Uranium-235. Fission occurs and 2-3 neutrons + an isotope of Uranium is produced as a result.

    The mass of the reactants (neutron + Uranium-235) = mass of the products (2-3 neutrons and an isotope of Uranium) + Energy
    where the mass of the reactants > mass of the products


    So far this makes sense...


    But Q 1(a)(ii) in the June 2013 paper says "State and explain how the mass of a He-4 nucleus is different from the total mass of itsprotons and neutrons when separated."

    My answer was that the mass of the He-4 nucleus is greater than the mass of the separated protons and neutrons.

    But the correct answer according to the mark scheme is:
    -separated nucleons have a greater mass (than when inside anucleus)
    -because of the (binding) energy added to separate the nucleonsor energy is released when a nucleus is formed (owtte)


    Help! This is contradicting my understanding and I am panicking! My tutor insists that what I said at the beginning of this post is correct, but the AQA textbook + several online sources agrees with the mark scheme.


    Thanks
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    (Original post by CD223)
    It has been confirmed. Multiple newspapers have run the story too. I'd be surprised if it was all a spoof. Personally I'm gutted.


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    Why are you gutted? How does this have a negative effect on you, its just a different paper right?
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    (Original post by cajach)
    Can someone let me know if this is correct please!


    During fission and fusion processes, mass is converted into energy and this energy is released. The released energy is the binding energy, which is equal to the strong nuclear force energy. Since mass is converted into energy, the mass of the reactants > mass of the products.

    For e.g. a neutron is absorbed by Uranium-235. Fission occurs and 2-3 neutrons + an isotope of Uranium is produced as a result.

    The mass of the reactants (neutron + Uranium-235) = mass of the products (2-3 neutrons and an isotope of Uranium) + Energy
    where the mass of the reactants > mass of the products


    So far this makes sense...


    But Q 1(a)(ii) in the June 2013 paper says "State and explain how the mass of a He-4 nucleus is different from the total mass of itsprotons and neutrons when separated."

    My answer was that the mass of the He-4 nucleus is greater than the mass of the separated protons and neutrons.

    But the correct answer according to the mark scheme is:
    -separated nucleons have a greater mass (than when inside anucleus)
    -because of the (binding) energy added to separate the nucleonsor energy is released when a nucleus is formed (owtte)


    Help! This is contradicting my understanding and I am panicking! My tutor insists that what I said at the beginning of this post is correct, but the AQA textbook + several online sources agrees with the mark scheme.


    Thanks
    The beginning of your post is correct because that fission is not induced fission, that is no energy was supplied to cause the fission and so the energy released during the process resulted in a decrease in mass of the products.

    In the case of the june 13 question the nuclide is separated into its constituents. Naturally this doesn't happen and so energy equal to the binding energy of the targeted nuclide must be supplied to break it into its constituents. This energy supplied is now stored in the constituents of the nuclide in the form of mass, resulting in an increase of the mass of the separated protons and neutrons of the fissioned nuclide.


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    (Original post by Sbarron)
    Let's all talk about things we don't know about then!! And pretend we know and just ask each other questions out of textbooks with the answers in the back! Haha or pretend we don't know about stuff we do! Who knows... One of you could be AQA!
    In all honesty though I'm sure the papers have already been sent and I don't think they could ask us stuff just because we've been talking about it and learning it... Everyone's been doing that for the past two years!
    The papers were stolen and they're writing new ones. Maybe they're checking if anyone posted it here
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    We the all nighters
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    I can't sleep and I have C4 in 2 days wow thanks god

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    (Original post by Dante991)
    I can't sleep and I have C4 in 2 days wow thanks god

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    Same here OCR MEI C4 on Tuesday 16th
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    (Original post by PotterPhysics)
    That definitely doesn't sound too bad, I'm sure it's still an A* or a high A at least...

    Unit 5: Section A is good. Turning points is also good but you literally need to memorize the mark schemes if you want to get top marks. I think this is what people find so hard (hence low grade boundaries). I only picked it because I find the topics interesting and wanted to learn some basic special relativity.
    Hmmm. Praying for an A* in PHYA4 that compensates for a slightly worse PHYA5 but it's so hard to tell. Not only was PHYA4 controversial this year (typo, fairly easy MC compared to previous years, slightly more polarising questions like the damping question), but PHYA5 boundaries are lower. So even if PHYA5 feels the worse of the two exams it might turn out better haha.

    (Original post by Boop.)
    Why are you gutted? How does this have a negative effect on you, its just a different paper right?
    I just had hoped the questions would be of the 2015 style. I think they'll pull a lot of questions from the spec now given the short restrictions on time. And given the last minute rush, there's no guarantee that this paper will be typed correctly either!



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    (Original post by CD223)
    Hmmm. Praying for an A* in PHYA4 that compensates for a slightly worse PHYA5 but it's so hard to tell. Not only was PHYA4 controversial this year (typo, fairly easy MC compared to previous years, slightly more polarising questions like the damping question), but PHYA5 boundaries are lower. So even if PHYA5 feels the worse of the two exams it might turn out better haha.



    I just had hoped the questions would be of the 2015 style. I think they'll pull a lot of questions from the spec now given the short restrictions on time. And given the last minute rush, there's no guarantee that this paper will be typed correctly either!



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    The replacement exam will have been written at the same time as the one that got stolen. The only thing they will have to had to write on the replacement is the date!


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    I need to get close to an A to compensate for PHYa4....
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    (Original post by Mehrdad jafari)
    The beginning of your post is correct because that fission is not induced fission, that is no energy was supplied to cause the fission and so the energy released during the process resulted in a decrease in mass of the products.

    In the case of the june 13 question the nuclide is separated into its constituents. Naturally this doesn't happen and so energy equal to the binding energy of the targeted nuclide must be supplied to break it into its constituents. This energy supplied is now stored in the constituents of the nuclide in the form of mass, resulting in an increase of the mass of the separated protons and neutrons of the fissioned nuclide.


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    Thank you, it makes a bit more sense now

    1) In fission, energy must be supplied to the nucleus to separate it. The energy is absorbed by the nucleus and transformed into mass. Therefore the mass of the nucleus > mass of its fission products
    2) When comparing the mass of a He-4 nucleus with the mass of its constituent protons and neutrons (no actual fission reaction taking place): Binding energy must be released from the He-4 nucleus to be separated. Mass is converted into energy internally in the He-4 nucleus and released, so the mass of the He-4 nucleus < mass of its protons and neutrons.
    3) In fusion, mass of the reactants (e.g. nuclei) > mass of products (e.g. the formed nucleus), because the formed nucleus needs to absorb energy to keep itself intact. Mass is transformed into energy and the energy is stored in the nucleus as the strong nuclear force.

    Hope my understanding is correct!


    I should also have mentioned that in my previous example, the neutron is fired at the uranium-235 in a reactor core. This would be "induced fission" right?

    So would mass of reactants >/</= mass of products if it was induced fission?


    I appreciate the help!
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    According to one of the articles I read, it said that no a level physics papers were affected - but replacement or not guys, it will still be a normal paper trust me just know your stuff and Youre goooooood

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    (Original post by ubisoft)
    The papers were stolen and they're writing new ones. Maybe they're checking if anyone posted it here
    I read that the stolen papers didn't include AQA physics
 
 
 
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