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OCR M3 (non MEI) Wednesday 8th June

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Reply 61


This is brilliant, haha, put a smile on my face after a sh**ty exam
Original post by Muzzles
This is brilliant, haha, put a smile on my face after a sh**ty exam


Thanks :smile: both Mechanics exams dreadful as well! :'(
Reply 63


Terrific Hitler reacts ahahah
Reply 64
How many people are doing M4? After a difficult M2 and M3 I can't wait to see what stuff they'll throw into the M4 this year ahaha!

Also was w^2=98 and A=0.675 for the last question?
Well I got w^2=392 and A =0.225

w^2 = L/l = 24mg/0.6 = 392
(edited 7 years ago)
Reply 66
Original post by Miracle-
Well I got w^2=392 and A =0.225

w^2 = L/l = 24mg/0.6 = 392


Oh, I did (4m)a=4mg-24mg(0.1+x)/0.6
And so a=-392x/4 and so w^2=98.
Then 2.1^2=98(A^2-0.075^2), A=0.675. No idea if it's right, hopefully some method marks even if I'm wrong
(edited 7 years ago)
Original post by JoeyTr
Oh, I did (4m)a=4mg-24mg(0.1-x)/0.6
And so a=-392x/4 and so w^2=98.
Then 2.1^2=98(A^2-0.075^2), A=0.675. No idea if it's right, hopefully some method marks even if I'm wrong


Yeah your right
Original post by JoeyTr
How many people are doing M4? After a difficult M2 and M3 I can't wait to see what stuff they'll throw into the M4 this year ahaha!

Also was w^2=98 and A=0.675 for the last question?


That's what I got yeah, not sure what my a was though


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Reply 69
Original post by JoeyTr
Oh, I did (4m)a=4mg-24mg(0.1+x)/0.6
And so a=-392x/4 and so w^2=98.
Then 2.1^2=98(A^2-0.075^2), A=0.675. No idea if it's right, hopefully some method marks even if I'm wrong


I agree with w^2=98 but doesn't the equation you wrote give A=0.225? Also do you remember what you got for the time for the last part of Q7?
Original post by JoeyTr
Oh, I did (4m)a=4mg-24mg(0.1+x)/0.6And so a=-392x/4 and so w^2=98.Then 2.1^2=98(A^2-0.075^2), A=0.675. No idea if it's right, hopefully some method marks even if I'm wrong

Wait using your w I still get A=0.225In fact 2.1^2 = 98(0.225^2-0.075^2)

so w^2 = 98 a=0.225
Time I got 0.796 u?
allow that last question
Reply 73
Original post by Miracle-
Time I got 0.796 u?


0.888 seconds, what was your method?
anyone remember the jist of each of the first 5 questions? like which was the impulse one, which was the particle on a string going in a circle, which was the collision question, which was the one with resistive force of (1/8)x or something... and what were the others? (of the first 5 only, know the last 2)
thanks.
Original post by Muzzles
0.888 seconds, what was your method?



2/7 seconds from suvat. t = root(0.8/9.8)

3/4 of a period so 3/4 * 2pi/root98 = 0.476 s

the first bit from 0.075 above to 0 = sin-1(0.075/0.225)/root98 = 0.034s

most likely something wrong, how did you do it?
Reply 76
Original post by Miracle-
Wait using your w I still get A=0.225In fact 2.1^2 = 98(0.225^2-0.075^2)

so w^2 = 98 a=0.225


Oh yeah, deary me, must've divided by 9.8 instead of 98!
Reply 77
Original post by Muzzles
I agree with w^2=98 but doesn't the equation you wrote give A=0.225? Also do you remember what you got for the time for the last part of Q7?


Didn't get a time, other than the suvat 2/7 bit. Just w^2 and my wrong amplitude! Probably like 2 marks out of 7
Original post by JoeyTr
Didn't get a time, other than the suvat 2/7 bit. Just w^2 and my wrong amplitude! Probably like 2 marks out of 7


do you remember what question 2 and 3 were on?
Original post by Simonium1010
do you remember what question 2 and 3 were on?


One of the was the linear motion with variable forces question, the other was either impact question or SHM question


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