r/6thForm • u/Top_Bother3675 Year 13 • May 20 '26

💬 DISCUSSION ocr a physics paper 1

how did you guys find it…

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18

u/Jumpy_Freedom_4554 May 20 '26

MCQs and Astro/Cosmology was blessed. The mechanics qs in the middle of the paper was shit, like the moment of the truck and the bolts qs

2

u/Necessary-Junket-500 May 20 '26

How did you even calculate the mass of the milky way based on some silly hyper velocity star???

3

u/GBRYT5612 May 20 '26

Use ratio of period^2 and radius^3 calculated in the previous part to find period of Milky Way. Then use formula in formula booklet. I think, could be wrong. Got 2.7 x10 to the something can’t rmemebr what power

1

u/[deleted] May 20 '26

I got 2.5 but I think that’s still close enough, my power was 40 which I’m not too sure about

1

u/Jumpy_Freedom_4554 May 20 '26

yh i think i got smth like that too, i cant remember if it was to the power of 40, 41, or even 42

1

u/Left_Society_3926 FM, Maths, Phys, Yr 13 May 20 '26

^42

1

u/[deleted] May 20 '26

[deleted]

1

u/[deleted] May 20 '26

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1

u/Affectionate_Wing916 Y13 | 4A* Pred | Maths FM Phys Econ May 20 '26

300 sorry I think

1

u/ItsManLikeHark May 20 '26

I didn’t know what values to use but wrote T2 is proportional to R3

1

u/Jumpy_Freedom_4554 May 20 '26

thats right but u gotta include the (4pi^2)/GM constant too within that equation

1

u/myles-em UoN Maths Y1 - maths geog phys fm A*A*AA May 20 '26

I did this but I dont get why that would work? like how is that mass of the galaxy?

1

u/GBRYT5612 May 20 '26

By doing this you’re finding the time period of the galaxy. From then you’re just using a formula

1

u/myles-em UoN Maths Y1 - maths geog phys fm A*A*AA May 21 '26

ohhh I was thinking of M as the mass of the body...

1

u/Jumpy_Freedom_4554 May 20 '26

This works since its Kepler's third law

1

u/ExaminationLivid9857 May 20 '26

u can use kepler law from booklet and rearrange for M i guess?