# OCR M3 (non MEI) Wednesday 8th JuneWatch

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3 years ago
#101
when you get a particle in SHM you use the cos or sin equations but thats only if there motion starts at the amplitude or the center. this one started in between them 2 though, so would the equation be x=Asin(wt + p) where p is a phase shift translation that moves the graph of its motion back to the normal sin curve so you can do all your usual calculations with the sin graph.
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3 years ago
#102

Like that but the red one wouldnt be that far translated, it would be the brown one moved to the right slightly. so youl need a translation constant to get it back to the sin curve
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3 years ago
#103
i just realised you could start the motion model when it is at the bottom so there is no need for a phase shift wow im so sad. so glad that m2 was a good exam
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3 years ago
#104
Just worth noting that the January 2008 paper was roughly 88% raw for 100 UMS. I reckon this was a much harder paper.
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3 years ago
#105
(Original post by bred123)
when you get a particle in SHM you use the cos or sin equations but thats only if there motion starts at the amplitude or the center. this one started in between them 2 though, so would the equation be x=Asin(wt + p) where p is a phase shift translation that moves the graph of its motion back to the normal sin curve so you can do all your usual calculations with the sin graph.
Oh I see what you mean, usually refer to it as some offset epsilon, so it threw me off

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3 years ago
#106
(Original post by JoeyTr)
I know this probably sounds weird but how did everyone's classmates find it? I was the only person doing it at my school so didn't really get the perspective. I don't really think people on the StudentRoom is a fair sample of how difficult people found the paper generally haha!
Personally, I found it harder than all papers between 2005 and 2015. I still managed to solve it, but two SILLLLLLLYYYYY mistakes made me lose around 5~6 marks I guess....
My peers found it hard too, and some did not even finish the paper....
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3 years ago
#107
Can someone recall question 7 part (iii) please. I think I got a=-10x rather than a=-10gx !!! :'(

Also question 5 (part 1) would be helpful
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3 years ago
#108
Just found out I lost around 10 marks max... giving me 62/72....
Btw, did you guys know that for 7(iv), Amplitude is larger than distance between Equilibrium position and point of natural length, so need to use suvat again....
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3 years ago
#109
(Original post by Mandos)
Can someone recall question 7 part (iii) please. I think I got a=-10x rather than a=-10gx !!! :'(

Also question 5 (part 1) would be helpful
I got -40.....
5.i, it was mg(2-3cos()) and height was 5/3 a
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3 years ago
#110
(Original post by cam5morrison)
Just worth noting that the January 2008 paper was roughly 88% raw for 100 UMS. I reckon this was a much harder paper.
I agree. In fact, I thought it was harder than any paper between 2005 and 2015
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3 years ago
#111
I made the same mistake as you, and got a=-40gx, but I realise now that when you equate tension-weight=ma (or something like that) your m in ma, is actually 4m, since it's a given quantity from the particles coalescing to have mass 4m. I just wrote ma and didn't think about it...

(Original post by JxK^2)
I got -40.....
5.i, it was mg(2-3cos()) and height was 5/3 a
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#112
(Original post by JxK^2)
I got -40.....
5.i, it was mg(2-3cos()) and height was 5/3 a
I got -40g lol
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3 years ago
#113
Anyone here doing M4 as well?
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1 year ago
#114
what are we thinking for grade boundaries? Didn't really get the last part of the last question but everything else was ok in my opinion. Not really too sure on my distance for the circular motion/projectile question
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1 year ago
#115
(Original post by Nimakarshenas)
what are we thinking for grade boundaries? Didn't really get the last part of the last question but everything else was ok in my opinion. Not really too sure on my distance for the circular motion/projectile question
Not sure maybe ~ 52 for an A? Felt easier than last year, similar in difficulty to 2016 I thought.
For circular motion projectile I got something like 16.6 root a but I think I might have ****ed up somewhere.
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1 year ago
#116
idk my school found it so easy, like according to them deffo 60 for an A
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