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

1. Hey guys, why do you you not include the binding energy of neutrons :/ ??

2. What does energetically favorable mean in nuclear fisson/fusion
3. (Original post by Me123456789)
Can someone explain this question please

The Treptow Giant Telescope in Berlin is the longest moveable refracting telescope on
Earth. Some of its properties are summarised below:

distance between the objective lens and eyepiece lens = 21 m
angular magnification = 210
objective lens diameter = 0.68 m

1 (b) (i) Calculate the focal lengths of the eyepiece lens and objective lens of the Treptow Giant
Telescope
Basically as the distance between the two lenses is 21m you know that fo + fe =21, a formula for magnification is fo/fe. So fo/fe =210. If you rearrange that to get fo=210fe and sub that into fo+fe=21 you'll end up getting 210fe+fe=21.... 211fe=21.... fe=21/211=0.1 roughly. You then sub that into fo+fe=21
4. In calculating the mass defect:

Individual constituents masses - mass of the nucleus

do we need to include the mass of the electrons around the nucleus?
5. (Original post by a.a.k)
Ok now i am confused.
Attachment 431393

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He said june 14 ?
6. What are the popular predictions for section A and Astro?

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7. (Original post by NightStrider)
He said june 14 ?
Yeah but this is same type of question or is it not

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8. (Original post by MrScarecow901)
In calculating the mass defect:

Individual constituents masses - mass of the nucleus

do we need to include the mass of the electrons around the nucleus?
Nope, just the protons and neutrons - just remember that this section is all to do with the nucleus only and focuses on it a lot

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9. (Original post by a.a.k)
Yeah but this is same type of question or is it not

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Not at all, there you are given masses but in june 14 you are given binding energy per nucleon
10. Anyone doing medical physics tomorrow for their optional unit? How is everyone feeling for it?
11. (Original post by RobHunter97)
Feel confident for this exam. Unit 5 is my strong point, and I've managed to get 120 UMS on every past paper under exam conditions. However, I was confident for the Unit 4 one and that went awfully, so I am a little on edge! I feel like the six markers could be horrible

I'm also too worn out to revise, this is my 11th and final exam. Anyone in a similar situation?
Unit 5 is my weak point :/ I've had 11 exams so far, but have 5 to go (include unit 5 tomorrow) fml
12. I really hope that tomorrow's paper will be like June 10/ June 11 - they were so amazingly beauyiful. I prefer an easy paper with high boundaries

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13. (Original post by Joew8798)
Basically as the distance between the two lenses is 21m you know that fo + fe =21, a formula for magnification is fo/fe. So fo/fe =210. If you rearrange that to get fo=210fe and sub that into fo+fe=21 you'll end up getting 210fe+fe=21.... 211fe=21.... fe=21/211=0.1 roughly. You then sub that into fo+fe=21
Makes sense now, thank you
14. Been through astrophysics like once in class and feel like I know next to nothing lol, wasnt told about quasars too do we need to know those?
15. (Original post by Dante991)
Nope, just the protons and neutrons - just remember that this section is all to do with the nucleus only and focuses on it a lot

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Thank you, I got confused as I did an old spec Q that included electrons
16. (Original post by SuperMushroom)
The mass of them is so small that they can be assumed to be negligible
in the markscheme it does take in the mass of the positron?

if you look in the formula sheet it gives you the mass for it in amu
17. does anyone know if you times the atomic mass unit by 931 or 931.5 to give the energy in MeV?
18. What do people reckon a decent C at AS, and a U at A2 will make as an overall grade?
19. (Original post by Connahnieurzyla)
Been through astrophysics like once in class and feel like I know next to nothing lol, wasnt told about quasars too do we need to know those?
Quasars haven't come up recently so you might need to!
Basically, to summerise:
-believed to be the most distant objects in the universe
-believed to be some of the brightest objects in the universe
-have experienced extremely large red shift
-first discovered due their strong emission of radio waves
-can produce the same power output as several galaxies
20. (Original post by MrKlaus)
does anyone know if you times the atomic mass unit by 931 or 931.5 to give the energy in MeV?
As far as I know use 931.5 to be safe, but the last paper I did allowed 931 to be used

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