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

1. (Original post by superduperbob)
I put main sequence
-82 is definitely wrong if that's the absolute magnitude one, as it only goes down to -26
2. In the resolution question where lambda is between 1 and 5, which value of lambda were we supposed to use 1, 5 or 3?
For the one you got 160,000 i thought you were supposed to square them first then add them, and then divide by 3?
I initially thought this too. But I looked at the units, which were
So I calculated the mean. Then I just squared it all.
4. Guys did your paper for section b have R on the end of the code
5. (Original post by Lizzieee4)
For that did you work out Q for Q=mcT and Q=ml and add them ?
yes
6. (Original post by Lizzieee4)
For that did you work out Q for Q=mcT and Q=ml and add them ?
I did Q = mct + ml
7. (Original post by StarvingAutist)
No, you add it. The largest distance is when the earth is on the opposite side of the sun compared to.. the thing
Ahh ok seems I got that wrong then

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For the questions it said show that the value is 'about' x, such as show it was 1.4*10^-15 m and you get 1.43*10^-15, for the next part in the questions do you use 1.43 or 1.4? or doesn't it matter?
9. (Original post by superduperbob)
I put main sequence
I put main sequence as well in the end after changing from dwarf star, people at my school saying dwarf but I thought the power output was way too high to be a dwarf star
10. (Original post by StarvingAutist)
No, you add it. The largest distance is when the earth is on the opposite side of the sun compared to.. the thing
Yup!
I added 1AU + 2.57AU (largest distance) to get something like 3.57AU to get the largest possible distance.

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11. (Original post by fruity97)
I put main sequence as well in the end after changing from dwarf star, people at my school saying dwarf but I thought the power output was way too high to be a dwarf star
I thought this aswell

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12. Anyone get 2.07x10^6 m2s-2(might have been 7 cant remember) and get 4.7x10^4Jor around that?
13. (Original post by fruity97)
I put main sequence as well in the end after changing from dwarf star, people at my school saying dwarf but I thought the power output was way too high to be a dwarf star
i used the fact that its power output is similar to the sun, but much hotter
14. (Original post by SuperMushroom)
I thought this aswell

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I did it based on temp, it was 5,000K which is an orange star, so therefore it should be a main sequence star
15. (Original post by k9000)
Anyone get 2.07x10^6 m2s-2(might have been 7 cant remember) and get 4.7x10^4Jor around that?
I think I may have had 2.06x10^7 but otherwise yes I concur for both
16. (Original post by k9000)
Anyone get 2.07x10^6 m2s-2(might have been 7 cant remember) and get 4.7x10^4Jor around that?
Yeah something like that for the mean square speed
But my energy was different... It was like 1.6*10^7

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17. (Original post by SuperMushroom)
For the first question on astro as it gave the distance from the sun in AU and it wanted the distance to the earth so do you take away 1AU from the largest distance given and this would give the distance to the earth

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That's what I did. 2.57-1 AU and convert to metres. Hope that's right. I presume it wanted the distance between the centres and we didnt have to remove the radii.
18. (Original post by dominicwild)
I initially thought this too. But I looked at the units, which were
So I calculated the mean. Then I just squared it all.
Oh ok i have no clue if im right, i just remember when you derive the pressure of a gas (u1^2 + u2^2...) / Number of particles = mean squared value
19. (Original post by HenryHein)
I think it said largest distance, so you add 1AU not take away (3.57AU in total?)
did what i di !!!! many say taking away is right but surley if the earth is behind the sun and venus or whatever the distnce is add 1 ?
20. (Original post by Sbarron)
Now I'm far from the best student so DON'T go by these values but I just want to see if anyone got any the same as me.....

Nuclear and thermal:
0.05, 5.00
1.4*10-15 m
5.3*10-15 m
1.3*10^17 kgm-3
3.3*10-6 s-1
8.2*10^11
47000J
160000
319 K

Astro:
2.4*10^11
15m
-82
5000 K
97*10^6
8.8*10^21
4.9*10^17
I agree pretty much with all the Thermal and Nuclear ones! I did turning points section 2 though :3

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