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

1. (Original post by Bowenabc)
Did you calculate it by taking 1 AU from 2.57AU (whatever the furthest distance was)

or did you calculate it using a triangle with base 1 AU and legnth 2.57AU and take
hypotenuse?
You had to add 1 AU to 2.57AU and convert to metres
2. (Original post by chizz1889)
Yeah but it said you didn't need to include any apparatus details so it was basically just describing the measurements/calculations involved in the experiment
So you could literally just say, measure pressure at different temperatures at constant volume, where line crosses x axis blah, when T = 0 pressure is 0 as ke = 0 so v = 0, so no particles collide with wall.
3. (Original post by chizz1889)
You had to add 1 AU to 2.57AU and convert to metres
But how would you be able to see Vegas if it was on the otherside of the sun?
And what was your subsequent answers for the angle subtended by Vegas, and what did you write for discuss level of details the telescope can see?

Do you also remember how many marks these questions were worth?
4. Anyone posting an unofficial mark scheme? I would but I don't remember my answers...
5. (Original post by CD223)
Anyone posting an unofficial mark scheme? I would but I don't remember my answers...
How'd you find it mate? I thought astro was good apart from the 6 marker

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6. would it fair to say 50 max for an A ? (astro as it had some confusing ques, e.g. first ques many took away, 6 marker wave calculcation, etc. )
7. (Original post by Bowenabc)
But how would you be able to see Vegas if it was on the otherside of the sun?
And what was your subsequent answers for the angle subtended by Vegas, and what did you write for discuss level of details the telescope can see?

Do you also remember how many marks these questions were worth?
It wasnt a binary star otherwise minus 1 would have been correct, it just asked for the distance it didnt mention it could be seen
8. (Original post by SuperMushroom)
How'd you find it mate? I thought astro was good apart from the 6 marker

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Erm, it was an odd paper on the whole. Made some stupid mistakes. Thought the star was a main sequence as its power output was similar to the sun.
So you could literally just say, measure pressure at different temperatures at constant volume, where line crosses x axis blah, when T = 0 pressure is 0 as ke = 0 so v = 0, so no particles collide with wall.
Yeah but in more detail eg:
Pressure is directly proportional to temperature, measure the pressure for different temperatures and plot a graph of pressure against temperature. Plot a line of best fit and extrapolate backwards until it intercepts the x axis. This temperature is absolute zero. This is supported by the fact that for a fixed volume, P=kT where k is a constant, so when P = 0, T=0. This is because at this temperature the molecules have no kinetic energy so they don't vibrate and hence don't exert a pressure on the container. 😊 that's a six mark answer
10. (Original post by MangoFreak)
Maybe I'm wrong: I do that
11. Any polls for this?
12. Is ' obeys newtonian mechanics' correct for the ideal gas :[
13. (Original post by DomRauba)
Is ' obeys newtonian mechanics' correct for the ideal gas :[
Should be
14. (Original post by CD223)
Erm, it was an odd paper on the whole. Made some stupid mistakes. Thought the star was a main sequence as its power output was similar to the sun.

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15. (Original post by Disney0702)
Oooh i actually forgot to check. Did yours?
Our exams officer made a huge fuss over it!!
16. Astro : I got 3.0 m for the Diameter
16,000 K for Black body temperature
9.5 * 10 ^ 6 for Radius of the white dwarf
4.9 * 10 ^ 17 for the Seconds
-9.7 * 10 ^ -3 for Absolute Mag
4 days for period , 1.1* 10 ^ 5 for speed

Thermal : Density : 1.4 * 10 ^ 17
RMS : 2.1 * 10 ^ (SOMETHING)
Temperature : 320 Kelvins
Energy : 4.7 *10 ^ 4 J ( I think )

If anyone needs these
17. (Original post by RemainSilent)
It wasnt a binary star otherwise minus 1 would have been correct, it just asked for the distance it didnt mention it could be seen
Aw ****, I got mixed up with the second quesiton. Thought it was what is max distance it could be observed at.

Was the sub question after the angle subtended when Vegas is at min distance or max distance?
18. (Original post by DomRauba)
Astro : I got 3.0 m for the Diameter
16,000 K for Black body temperature
9.5 * 10 ^ 6 for Radius of the white dwarf
4.9 * 10 ^ 17 for the Seconds
-9.7 * 10 ^ -3 for Absolute Mag
4 days for period , 1.1* 10 ^ 5 for speed

Thermal : Density : 1.4 * 10 ^ 17
RMS : 2.1 * 10 ^ (SOMETHING)
Temperature : 320 Kelvins
Energy : 4.7 *10 ^ 4 J ( I think )

If anyone needs these
Got all the same for astro.

Can't really remember thermal
19. (Original post by EconFan_73)
Got all the same for astro.

Can't really remember thermal
good to hear bro
20. why is everyone so happy i swear it wasn't THAT easy?!

no clue for the 6 marker, though i could do the astro one
thought it was a main sequence star
got a different value for the magnitude
lost like 4 marks somwehere else

so thats like 16 marks lost...that i know of...

could still be an a?

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