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# Official OCR A G481 mechanics 20th May 2013 watch

1. (Original post by Joeyoh9292)
What was the second way? I got f = ma / w = fx --> w = max --> SUVAT for ax --> ax = 1/2v^2 so w = m1/2v^2 (or 1/2mv^2)
You can do it by integration.
2. (Original post by teachercol)
You can do it by integration.
Would you still get credit by integrating, surely they won't expect everyone who does physics to know about integration?
3. (Original post by sohailkm96)
For the perpendicular component you need to use the cos of the angle, so it was 8x10^-5 (if im right) x cos30

For the parallel component you need to use the sin of the angle, so it was 8 x 10 ^-5 x sin30
Oh thanks that's what I did, I wasn't sure about it
4. Teacher Col did you think it was a hard paper?
5. Oh yeah, I've remembered a question which no-one has talked about in this thread. I wasn't sure what to do on the question where it asked for the input and output power (or something like that). What did you guys get? I hope y'all know what question I'm talking about.
6. (Original post by teachercol)
You can do it by integration.
How would you do it by integration?
7. (Original post by sohailkm96)
Would you still get credit by integrating, surely they won't expect everyone who does physics to know about integration?
They dont expect it. They expect F = max and suvat.
But if you integrated F.dx = mvdv = work done then they'll give you the credit
8. Anyone else think this physics exam was equally as hard as the january exam?
9. (Original post by Ferrari_1996)
Oh yeah, I've remembered a question which I don't think anyone has talked about in this thread. I was confused on the question where it asked for the input and output power. What did you guys get? I hope y'all know what question I'm talking about.
that question was retarded

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10. (Original post by Ferrari_1996)
Oh yeah, I've remembered a question which I don't think anyone has talked about in this thread. I was confused on the question where it asked for the input and output power. What did you guys get? I hope y'all know what question I'm talking about.
For the output power it's just the gravitational energy gained divided by time (I think), then the input power, as the output power is 30% efficient, you can find out what 1% of the input power is then times that by 100 to get input power.
11. (Original post by sohailkm96)
Would you still get credit by integrating, surely they won't expect everyone who does physics to know about integration?
Yes, because it is still correct mathematics. They can't mark you down for using correct maths, otherwise the exam board would have a problem when people complain about not getting the marks for it.

What was the correct answer for the trolley acceleration anyone? I stupidly got the resultant of the two springs wrong so I ended up with an acceleration of 3.5m/s^2.
12. (Original post by Ferrari_1996)
Oh yeah, I've remembered a question which I don't think anyone has talked about in this thread. I was confused on the question where it asked for the input and output power. What did you guys get? I hope y'all know what question I'm talking about.
Input was output/0.3 (as it had 30% efficiency). I can't remember how you were to find Output. All I know is that they ordered it very specifically, so you used each of the previous one mark questions in the next. It was a 4 mark question made quite easy by splitting it up.
13. (Original post by SamBBB)
Anyone else think this physics exam was equally as hard as the january exam?
I thought it was harder:/
14. (Original post by ss2012)
that question was retarded

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This question confused me so much, I did 30% for the ouput and 100% for the input?
15. (Original post by teachercol)
They dont expect it. They expect F = max and suvat.
But if you integrated F.dx = mvdv = work done then they'll give you the credit
Ahh okay thanks!
16. Anyone got an electronic copy of the paper?
17. has anyone got the paper??
18. (Original post by metabalo)
Yes, because it is still correct mathematics. They can't mark you down for using correct maths, otherwise the exam board would have a problem when people complain about not getting the marks for it.

What was the correct answer for the trolley acceleration anyone? I stupidly got the resultant of the two springs wrong so I ended up with an acceleration of 3.5m/s^2.
Ah okay, and I'm pretty sure 3.5ms^-2 is right.
19. (Original post by SamBBB)
Anyone else think this physics exam was equally as hard as the january exam?
I would say it was harder IMO.
20. (Original post by metabalo)
Yes, because it is still correct mathematics. They can't mark you down for using correct maths, otherwise the exam board would have a problem when people complain about not getting the marks for it.

What was the correct answer for the trolley acceleration anyone? I stupidly got the resultant of the two springs wrong so I ended up with an acceleration of 3.5m/s^2.
So far that's the consensus (and my answer). The next most-written answer is 14. You had to find B-A because A was pulling on B, which had more force, so it was larger force - lesser force (thus B-A). Reasoning is that they're both initially stretched.

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