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

I used 3cm and 30, i looked it up and 3 should be ok but i think Beta is like 15cm which is half as much so idk, but they'll definitely be a range

Did anyone mention 'self sustaining' in the describing a chain reaction question along with induced fission and neutrons released and critical mass?

Range of alpha and beta I put as 5cm and 30cm. Do you thin k there'll be a range?

I got 3.0m for the diameter of the telescope.

Wasn't the abs magnitude 1.98(1) - M = 5log(25/10)
Well **** that 1 I added changes it significantly, do you think they'll accept it?

Yes they are all for the rewritten paper which you sat, they rewrite each optional paper as a safety precaution when they rewrite the section a paper

I stupidly said main sequence and just used 2.57AU in the first question. I also said extrapolate in the six marker despite showing a graph with a temperature scale in kelvin so I've lost so many marks :/
same i said main sequence by mistake, but you should be method marks saying that temp decreases from 0 to M! I only used 2.57 AU seems so obvious now! i think many people will have made silly mistakes despite it being so straight forward ie not as high grade boundaries as you may think!

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We were told to write the R on the front of our paper! They hadn't come out in the printing

For anyone who did applied, what did you get for moment of inertia before the 6 marker? I got 4.4x10^-2, but my mate got 5.something?

Alpha was 0.1m and beta is 1m

Ah I just remember in past papers it's said beyond 30cm a source must be gamma as remaining types will not reach this far?

I've not looked up any answers bar what's on here. I thought the star was a main sequence as its power output was similar to the sun :/

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how do you know?

Really well maybe they do accept 30cm i hope so, obviously different sources will have different values as it varies so hopefully 30cm is in AQA's range

My answers for the questions that didn't have a "show that the answer is this" were:

Thermal and Nuclear
Range of $\alpha$ = 0.1m
Range of $\beta$ = 2.0m
Density = $1.63 \times 10^{17} kg m^{-3}$
Number of nuclei = $2.35 \times 10^{17}$
Energy used = 47000J
$\left(C_{rms}\right)^{2} = 2.07 \times 10^{7} m^{2} s^{-2}$
Temperature = 319K

Astrophysics
Maximum distance = $5.36 \times 10^{11} m$
Diameter = 15m (unsure about this)
In the 6 mark essay my period was 4 days, and my velocity was 109800 ms-1
Magnitude = -0.01 (definitely derped on this; 1sf and I missed the minus lmao)
Temperature = 16100K
White dwarf radius = $9.37 \times 10^{6} m$
Black hole radius = $2.95 \times 10^{13} m$
Age of the universe = $4.96 \times 10^{17} s$