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

1. (Original post by Dante991)
Anyone else think the grade boundaries will increase this year? Last year they were so low lol

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I'd say they're likely to go up this year just because they can't really go down any further! Not necessarily by a lot though, 2013's were really low too, and it didn't feel like either of them were super hard papers?
2. Hey, would anyone be able to post how to derive the kinetic theory model as how they would want you write it in an answer? I just want to learn it so I can nail it if it comes up - sorry for the re-post
3. How do you relate count rate, activity and intensity? Or can you not? This confused me on the June 13 6 marker
4. 3bi) on June 2008 is really bugging me!!!!!!!!!
5. Would MAXIMUM angular resolution actually be the SMALLEST angle it can resolve at?
6. (Original post by ZedRigby)
Hey, would anyone be able to post how to derive the kinetic theory model as how they would want you write it in an answer? I just want to learn it so I can nail it if it comes up - sorry for the re-post
Molecules move in rapid random motion at a range of speeds. Since they have velocity they therefore also have momentum. They collide with the wall containers elastically and undergo a change in momentum. Since Force is equal to the rate of change in momentum the molecules must feel a force and also exert an equal and opposite force on the container walls (which is equal to -2mv). Since pressure equals force/area there is a pressure.

That in a basic way maybe? I may have missed something out
7. Can someone please explain what Hydrogen Balmer absorption lines are and how they are produced in ghe spectrum of a star? Thanks.
8. For those of you asking for it, here's what I'd write for the derivation of kinetic theory:

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9. Is the resolving power the angle subtended by the observer to the centers of two objects or something else?
10. Thanks to those who helped with the kinetic theory, appreciate it
11. (Original post by you-only-live-once)
Yes i know! what do you think will be the 6 marker?
I'm thinking we might get a six-marker about the eye, there hasn't been one on the current spec papers so far. For example, explain for a light ray enters the eye, and how it gets received by the brain. Or maybe something about different vision defects, causes and how to fix?

Might be one about comparing some scan types, but they tend to be 2-4 markers really.
Could be one about surgery - endoscopes + why is laparoscopic surgery good, that hasn't featured at all really so far.

If only they'd give us 'Describe the events in one heart beat' again like in 2014!
12. Can someone link me to some good information or tell me about heat pumps and refrigerators
13. (Original post by slaven123)
No brightness. Question 2b(ii) on june 2010.
http://filestore.aqa.org.uk/subjects...W-QP-JUN10.PDF
The scale is logarithmic so each if you decrease by one this star is 100^1/5 times brighter, or if you decrease by 4 for example this star is 100^4/5 times brighter
14. anyone doing applied physics?
Also for section a (nuclear) i have a feeling that nuclear excited states and medical tracers may come up
15. Has anyone done june 14 core question1,
why we do not need to consider the mass of the neutrons?? Apparently in the exam report, many ppl did add the neutrons..
16. (Original post by DCMed96)
Has anyone done june 14 core question1,
why we do not need to consider the mass of the neutrons?? Apparently in the exam report, many ppl did add the neutrons..
look and binding energy per nucleon graph, nuclie with nucleon number 1 has zero binding energy per nucleon
17. (Original post by DCMed96)
Has anyone done june 14 core question1,
why we do not need to consider the mass of the neutrons?? Apparently in the exam report, many ppl did add the neutrons..
you dont use the masses.
You calculate the energy released using the change in binding energy.
Seeing as the neutrons are already free, they don't have any binding energy
18. (Original post by DCMed96)
Has anyone done june 14 core question1,
why we do not need to consider the mass of the neutrons?? Apparently in the exam report, many ppl did add the neutrons..
Neutrons do not have a binding energy as they are on their own and not part of a nucleus so do not need to be taken into account.
19. 6 marker predictions for astro and core anyone?
20. (Original post by slaven123)
Neutrons do not have a binding energy as they are on their own and not part of a nucleus so do not need to be taken into account.
(Original post by johnh545)
you dont use the masses.
You calculate the energy released using the change in binding energy.
Seeing as the neutrons are already free, they don't have any binding energy
(Original post by getback339)
look and binding energy per nucleon graph, nuclie with nucleon number 1 has zero binding energy per nucleon
Thanks for the quick response!!!

Anyone guess what will be on this year's six marker? (what can be the hardest thing they can throw on us) considering we are all gonna do the R place instead thanks to the lost van.....

Anyone doing med phy as well>

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