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

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http://filestore.aqa.org.uk/subjects/AQA-PHYA51-QP-JUN14.PDF can anyone please explain why you dont include the neutrons in 1B)ii. ?? thanks :smile:
Original post by oonic0rn
http://filestore.aqa.org.uk/subjects/AQA-PHYA51-QP-JUN14.PDF can anyone please explain why you dont include the neutrons in 1B)ii. ?? thanks :smile:


neutrons don't have any binding energy :smile:
Original post by InNeedOfHelpASAP
Thank you!:smile:


No problem mate good luck tomorrow!
Original post by roar96
neutrons don't have any binding energy :smile:


oooh!! do you know why that is, or is that just a fact we are supposed to know?:tongue:
Reply 2104
Original post by danny9253
PLEASE SOMEBODY HELP ME ANSWER THIS QUESTION

I get 237.9688u,87.72405u, 4.03468u respectively for the masses but these seem to be greater than on the mark scheme and i can't understand why??

What paper is this?
Original post by oonic0rn
oooh!! do you know why that is, or is that just a fact we are supposed to know?:tongue:


Neutrons aren't bound to anything, they're just by themselves
Reply 2107
Original post by oonic0rn
oooh!! do you know why that is, or is that just a fact we are supposed to know?:tongue:


I thought neutrons do have a binding energy, they're potential energy falls to a constant as they come within range of the strong nuclear force and hence they must lose mass due to E=mc2? Unless I've missed something out you would include neutrons when calculating binding energy or energy released in a nuclear reaction...
Original post by oonic0rn
oooh!! do you know why that is, or is that just a fact we are supposed to know?:tongue:


Someone earlier mentioned the fact that they're not bound to anything therefore their binding energy is 0?

It's just been something I've learnt :dontknow:
Which graphs do we need know off by heart lol?
Original post by InNeedOfHelpASAP
Hi guys, I'm a private candidate and have been studying from home. I've learned the whole Unit 5 syllabus and have practiced all the past paper exams because I'm not quite sure which papers I'm supposed to take and why there are so many?:| If anyone could steer me in the right direction, that would be great because I think I've probably covered more than I needed to?


I hope you haven't learnt every optional topic 😳😳😳😳


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Original post by MSB47
I thought neutrons do have a binding energy, they're potential energy falls to a constant as they come within range of the strong nuclear force and hence they must lose mass due to E=mc2? Unless I've missed something out you would include neutrons when calculating binding energy or energy released in a nuclear reaction...


If your calculating the energy released using the change in mass, then yes neutrons are included in the calculation. But in this situation it was just about the binding energy of the nuclei. Seeing as a neutron has already split from the neutron it has no binding energy and isnt included.
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Original post by danny9253
PLEASE SOMEBODY HELP ME ANSWER THIS QUESTION

I get 237.9688u,87.72405u, 4.03468u respectively for the masses but these seem to be greater than on the mark scheme and i can't understand why??


I came across the same question, I assumed that since it was the syllabus they were given the mass already, and they had to use that


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Original post by oonic0rn
http://filestore.aqa.org.uk/subjects/AQA-PHYA51-QP-JUN14.PDF can anyone please explain why you dont include the neutrons in 1B)ii. ?? thanks :smile:


I think in our course, There is no information on binding energy of protons and nucleons separately, Binding energy per nucleon is simply the average binding energy of a proton and neutron in a certain nucleus.

Neutrons that are not in a nucleus thus have no binding energy as binding energy is the energy released when a nucleus formed, which is determined by the mass defect. As there is no nucleus, no mass defect, hence no binding energy for thermal neutrons.
(edited 8 years ago)
Reply 2116
Original post by johnh545
If your calculating the energy released using the change in mass, then yes neutrons are included in the calculation. But in this situation it was just about the binding energy of the nuclei. Seeing as a neutron has already split from the neutron it has no binding energy and isnt included.


ohh my bad i misread the question thanks :smile:
Original post by Klaxoii
I came across the same question, I assumed that since it was the syllabus they were given the mass already, and they had to use that


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That was my thinking too since you have to be given the relative masses in order to work out mass defect. Thanks
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