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

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?

How'd you find it mate? I thought astro was good apart from the 6 marker


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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.

Maybe I'm wrong: I do that

Is ' obeys newtonian mechanics' correct for the ideal gas :[

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.

Oooh i actually forgot to check. Did yours?

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

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

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

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?

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

Wasn't the abs magnitude

1.98(1) - M = 5log(25/10)

For the first tick box I put alpha, I was a bit unsure since it said X-ray as well, but out of alpha beta and gamma alpha is the most ionising.
The the fill in the table I put 0.05 m for alpha and 2.0 m for beta.
The the reason why the gamma count decreased I put about the inverse square law. Then for what affects alpha as on the human body, I put that the greatest hazard is, if it gets into your body as it can cause breaks in your DNA causing mutations. For the reason about alpha scattering I put that it says the same as they are just isotopes same number of protons but a different number of neutrons, and only the number of protons matters. Then for chain reaction said a neutron collides with a uranium nucleus releasing further neutrons which can cause another fission event. Then said the moderator slows down the neutrons released till they reach fissile speeds and can cause further fission reaction, and the moderator absorbs the neutrons KE, then said the casing of the reactor absorbs neutrons which cause the nuclei to become unstable and then emit beta- . and for the motion of the particles for the equation PV=1/3 Nm(Crms)^2 I put that they have random motion and do not collide with any of the other molecules in the container the mean square speeds squared them all added them together and divided by 3. Then for astro I did 2.57-1 and times by 1.50x10^11. then for the bit below did Tan(angle)=(diameter/distance) The tick box asking if it was a main sequence star, dwarf or a red giant I put a dwarf as it seemed quite small, and for the definition of black hole I said the escape velocity is greater than the speed of light.