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AQA Physics PHYA5 - 28th June 2016 [Exam Discussion Thread] watch

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    (Original post by 124375)
    In question 1bii of June 2014 why is the mass of the neutrons ignored??? I don't get it!
    i saw that as well,i have no idea lol
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    Anyone got notes?
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    Should I do papers or read notes?


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    (Original post by nyxxllis)
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    I believe you're meant to know the average binding energy per nucleon for iron because it's the highest value. It is about 9MeV. I know if they ask you to draw the graph you need to show the max value at around 9 MeV for a value of A around 50.
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    Anybody else find they repeatedly miss out on marks because of how the mark scheme is phrased? I basically write the right thing every time but somehow manage to not get the marks, so annoying
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    (Original post by twallien)
    I believe you're meant to know the average binding energy per nucleon for iron because it's the highest value. It is about 9MeV. I know if they ask you to draw the graph you need to show the max value at around 9 MeV for a value of A around 50.
    Yeah, i'm aware it's 8.89 MeV but it specifically asks you to calculate it. In the markscheme it seems to include a value for the mass of the isotope to something like 4dp. I can't believe that we're meant to know that by heart?
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    (Original post by Whizbox)
    Any turning points 6 marker predictions? Motivation for this exam is at a new low, just one more
    Know that feeling bro :bebored:
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    (Original post by nyxxllis)
    Yeah, i'm aware it's 8.89 MeV but it specifically asks you to calculate it. In the markscheme it seems to include a value for the mass of the isotope to something like 4dp. I can't believe that we're meant to know that by heart?
    You do 56 times u to find it.
    Then working it out as usual by finding the ones for individual protons and neutrons. You then subtract. and finish up.
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    (Original post by nyxxllis)
    Yeah, i'm aware it's 8.89 MeV but it specifically asks you to calculate it. In the markscheme it seems to include a value for the mass of the isotope to something like 4dp. I can't believe that we're meant to know that by heart?
    The AQA formula sheet provides the rest mass for protons and neutrons so just finding number of protons and the number of neutrons and multiplying them by thier respective rest masses
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    (Original post by twallien)
    The AQA formula sheet provides the rest mass for protons and neutrons so just finding number of protons and the number of neutrons and multiplying them by thier respective rest masses
    What you said doesn't make sense?
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    (Original post by Craig David)
    You do 56 times u to find it.
    Then working it out as usual by finding the ones for individual protons and neutrons. You then subtract. and finish up.
    I may be wrong but this would surely just give the total binding energy of the atom?
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    (Original post by Craig David)
    What you said doesn't make sense?
    This would completely rid any mass defect, the individual components of the atom have more mass than the actual atom so doing this there would be no way to calculate the mass defect because there wouldn't be any?
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    (Original post by Craig David)
    What you said doesn't make sense?
    Can you post the mark scheme answer?
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    (Original post by 124375)
    In question 1bii of June 2014 why is the mass of the neutrons ignored??? I don't get it!
    Binding energy is the amount of energy required to separate a nucleus into its constituent nucleons. No energy is required to separate a neutron because it wasn't part of the nucleus in the first place.
    I think anyway..
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    (Original post by nyxxllis)
    This would completely rid any mass defect, the individual components of the atom have more mass than the actual atom so doing this there would be no way to calculate the mass defect because there wouldn't be any?
    Exactly. You then divide by the amount of nucleons.

    What he said would give you zero. Doesn't make much sense. You are back to the starting point.
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    (Original post by twallien)
    Can you post the mark scheme answer?
    I want to know where the 55.93493 figure comes from, i can do the rest. This appears to be the measured value for the mass of the atom but isn't stated in the question anywhere?
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    (Original post by Windowswind123)
    Binding energy is the amount of energy required to separate a nucleus into its constituent nucleons. No energy is required to separate a neutron because it wasn't part of the nucleus in the first place.
    I think anyway..
    I got stuck on that question too and I though that since neutrons have rest energy wouldn't that be included? Otherwise where does that energy come from


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    (Original post by Craig David)
    What you said doesn't make sense?
    Looking at the question I think the question was meant to provide the actual rest mass of iron, the 55.93493u. it might have been in an earlier part of the question because we're not meant to memorise that.
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    Can anyone explain question 1c to me please? thanks http://filestore.aqa.org.uk/subjects...C-QP-JUN12.PDF
 
 
 
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