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# Official Thread For OCR Physics A G484 Jan 2011 Watch

1. (Original post by Masderchef)
I can't understand myself why the v^2=GM/r was worth 4 marks. My only guess is that they wanted us to derive the equation first, (as it's not on the data sheet). So I did.

What did you get for your amplitude in the tide question? and the last moles question too?
Yeah looking back on it I think they did want you to derive it... but I didn't think to do it
Amplitude is 2.5m, because it is oscillating about the mid point of the two tides, which is 15.5m
Last moles question... I think I got 0.02 kg lost.... I was kicking myself as I had done an identical question last night and forgot the method to do it!
2. this was way harder than jan 10 an very much harder than june 10... do u think 44/60 wud scrape an A??
3. (Original post by Ben Adams)
Yeah looking back on it I think they did want you to derive it... but I didn't think to do it
Amplitude is 2.5m, because it is oscillating about the mid point of the two tides, which is 15.5m
Last moles question... I think I got 0.02 kg lost.... I was kicking myself as I had done an identical question last night and forgot the method to do it!
I got 5 for the amplitude(18-13). I think it might be wrong though.

I might have got 0.0260Kg for the last part. How did you get to your answer for this?
4. I think the amplitude is 2.5m min was 13 and max was 18 so equilibrium was 15.5 and amp is distance from the equilibrium position...
Apropos finding the radius, I used keepers third and T=2pi/v to get the right answer. As the question didn't say from first principles, do you reckon I'd get the marks? XD
5. (Original post by rob...)
I thought the helicopter question took time to think about. It wasn't exactly a normal mechanics question.

"Newtonian World"? More like "Physics: All Aspects of".
What a fantastic way of putting it

That helicopter question took me ages to work out what I was doing... I left it and came back to it at the end with my answer squished in at the bottom of the page underneath a pile of nonsensical equations and working out

I got something like 6126.something, I feel like I can literally recite off my answers to every question at the moment...
6. was three significant figures ok for the majority of the answers?
7. (Original post by gdsffdes)
was three significant figures ok for the majority of the answers?
I gave my answers to the number of sig figs they used for the values they gave in the question.
8. 51/60 around for this paper enough to get an A?
9. (Original post by yu80359)
51/60 around for this paper enough to get an A?
more than enough. Grade boundaries will probably be very low maybe around 43/42 for an A. I was lucky in that I like papers with more calculations.
10. Has anyone got a copy of the paper they could upload?
11. A copy of the paper would be really nice

Does anyone remember whether they had to add the radius of the earth for the four mark satellite calculation question? Someone in school mentioned that they did. Getting sort of scared, since I don't remember doing that

Edit: Then again, that's not possible. I don't think we were given the radius of the earth in the question anyway.
12. (Original post by FruitsPunchSamurai)
A copy of the paper would be really nice

Does anyone remember whether they had to add the radius of the earth for the four mark satellite calculation question? Someone in school mentioned that they did. Getting sort of scared, since I don't remember doing that

Edit: Then again, that's not possible. I don't think we were given the radius of the earth in the question anyway.
No we didn't as we weren't given the radius - the distance was from the centre of the earth so there is no need for the radius, did you get something like 2.7-2.9x10^7 m?
13. (Original post by Kooper)
Has anyone got a copy of the paper they could upload?
I'll try and get one on Monday and upload it here,
14. (Original post by jammydav93)
No we didn't as we weren't given the radius - the distance was from the centre of the earth so there is no need for the radius, did you get something like 2.7-2.9x10^7 m?
I can't remember the exact value, but I remember my working.

GM/r = v^2
After that it's just number crunching.
15. (Original post by FruitsPunchSamurai)
I can't remember the exact value, but I remember my working.

GM/r = v^2
After that it's just number crunching.
it was 2.92 x10^7
16. (Original post by Michael_4180)
it was 2.92 x10^7
how many marks do you think ill get for deriving v^2=GM/r
17. (Original post by sc0307)
how many marks do you think ill get for deriving v^2=GM/r
Probably 1 mark for deriving it, 1 mark for re-arranging it to make r the subject, 1 for substituting the values, and the final mark for an accurate answer.
18. (Original post by sc0307)
how many marks do you think ill get for deriving v^2=GM/r
Probably one mark for derivation, second for rearranging (if you did that as well). Just a guess though

Edit: I was beaten to it
19. Lol thanks for answers, sadly i rearranged wrong hopefully i'll get a mark for substituting the numbers into v^2=GM/r
20. I think it was quite an easy paper, but srsly WHY was there a KWh question???

That's not exactly in the unit 4 syllabus.

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