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# OCR Physics A newtonian World 20/6/16 Unofficial Mark Scheme

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1. @teachercol Hi, do you think an assumption for the lead experiment could be that there is no time between inversions of the container? thanks!
2. (Original post by Jm098)
Looks like i got 45... Pushing for an A*? lol
Same! (I think anyway lol probs gonna drop sub 40 tho). Hopefully 45 is around 80/90.
Same! (I think anyway lol probs gonna drop sub 40 tho). Hopefully 45 is around 80/90.
how you been getting on in past papers?
4. (Original post by Jm098)
how you been getting on in past papers?
Over 50 in all I've done bar 2014, I think something like 47 for that one. This paper however I was not expecting to be so abstract, so it took a while for me to find my concentration. The binary star question was the main culprit. Wbu?
Over 50 in all I've done bar 2014, I think something like 47 for that one. This paper however I was not expecting to be so abstract, so it took a while for me to find my concentration. The binary star question was the main culprit. Wbu?
Yeah haha sounds like you're in exactly the same boat as me! That question was bad but I made too many silly errors e.g. that KE/EPE graph
6. (Original post by Jm098)
Yeah haha sounds like you're in exactly the same boat as me! That question was bad but I made too many silly errors e.g. that KE/EPE graph
Ah I made other errors two mate. Hopefully the grade boundaries are kind!
7. (Original post by teachercol)
5/4pi difference is same as 3/4pi difference so should get the mark.
Thank you sir!
8. Got anywhere from 45-51 based on ecf. Happy with that, reckon I have a decent chance of an A*, and if not at least close I hope.
9. teachercol For the binary star question, could you treat the centre of the two circular motions to be a body of mass (M1 + M2 all divided by two) as the question said the two stars orbit about their centre of masses. By doing this could one then say : (v1)^2/R1 = (G)(M1+M2/all divided by two)/ (R1)^2 or (V2)^2/R2 = G(M1+M2/all divided by two)/ (R2)^2? If unclear I'll attach a diagram
10. Desperate for an accurate prediction of the grade boundaries
11. (Original post by Skylarkman)
Desperate for an accurate prediction of the grade boundaries
I think it will be similar to last years...

FULL 51
A* 47
A 43
B 39
C 35

Then again, that's probably me being a bit too hopeful. A lot of people seemed to find it much easier than I did
12. binary system is in the spec?
13. I think I completely misinterpreted Question 1. Didn't it say why these lines have the same gradient?
I said they were parallel lol and have the same change in y/change in x ratio. And for the triangles being a different area i just said they had different bases and perpendicular height so when you applied the formula for area of a triangle you would get a different area. oh my lord.
14. teachercol

Going back to q5e, it seems you forgot that the eqn for Fgrav in binary star systems is F=GM1M2/(R1+R2)^2, because you went back and equated F=mv^2/R to F=GM1M2/R1^2 (forgetting one of the radii) hence getting the wrong result
15. I agree with you that the answer is wrong so worked through it again properly to check it. Do you agree with this answer?

16. Difficulty poll:
http://www.thestudentroom.co.uk/show...0#post65956530

17. (Original post by Kevinwong)

Posted from TSR Mobile
yeah, that answer gives me a chill
i got E^33 too
hope he is wrong
18. Ignore the number in the brackets, thats me tallying how many marks i dropped worst case.
If anyone could help put my mind at ease for some of these that'd be great.
2)
c)ii)
R = mg + Fsin55 = 92 x 9.81 + (8.25 x 25)sin 55
= 902.5+169 = 1071N (3)
I omitted the Multiple by 25 by 8.25 and instead did Weight plus 8.25sin55.
Is this likely to get 1 or 2 marks out of the 3? (-2/3)

Q3 a)iii)
Left in Pi :/
b) i) I just flipped the EPE curve, is that both marks out the window?
ii)&iii) I then calculated these using 80mJ opposed to 50, would I drop all of these marks, or would I get e.c.f? (-3/5)

Q5e) Used keplers third law and got 1.73*10^33 :/
Is that 3 marks out the window? Or could I (hopefully) get 2 for this method? (-2/3)

Q6)a) Possibly didnt answer in enough detail. (-1/2)
d) So stupid, was rushing at this point, stated 2x the energy input, but not 2x mass so said temperature would increase by 2. Ridiculously stupid. Would I get 1 mark for stating that energy input is doubled, or is it 1 mark for saying constant and 1 mark for correct explanation? (-2/2)

Q7)a) Not enough detail (-1/2)

Worst case 49/60. Very disappointed considering I was getting 58+/60 on my past papers. Absolutely kicking myself.
19. Whats the grade boundaries? Anything like 43 for an A?
20. (Original post by botnatsume)
yeah, that answer gives me a chill
i got E^33 too
hope he is wrong
I got 1.02*10^33, anyone else get this?

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