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OCR G492 Jan 2011 Advance Notice Article Watch

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    (Original post by Niro_93)
    Hi
    The question that confused me although it seemed like it should have been straight forward was the question about transmitter and to calculate the minimum separation. I believe this was in section A part where you first had to show wavelength was 300m. But i didnt know how to calculate the separation.
    I thought the areas where the signal is weak is were the waves are antiphase and interfere destructively i.e. they must be half a wavelength apart..
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    (Original post by TheTomD)
    I feel exactly the same. Just seemed like a load of random non-sense that was just asking for you to 'Explain...'...'Explain...' etc.

    I also just thought that was what the question wanted...after about 5 minutes sat there thinking 'Okay...what am I supposed to be calculating again?!'

    But I did it. How many sig. figs did you use?
    3 I think, but for some reason I used a recurring sign rather than ronding up. Now I think of it, pretty stupid thing to do :L

    The marks seemed a little off in quite a few places. 3 marks for that, which takes 5 seconds, then 1 or 2 marks on some other questions which took minutes.
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    (Original post by Tsatska)
    I thought the areas where the signal is weak is were the waves are antiphase and interfere destructively i.e. they must be half a wavelength apart..
    That's what I did. Think I had 330.something for the wavelength, and just did 330/2 for the seperation.
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    (Original post by Swindan)
    3 I think, but for some reason I used a recurring sign rather than ronding up. Now I think of it, pretty stupid thing to do :L

    The marks seemed a little off in quite a few places. 3 marks for that, which takes 5 seconds, then 1 or 2 marks on some other questions which took minutes.
    Exactly!
    It didn't seem right at all. Part of the reason I felt so stumped was because of those questions that seemed simple, but were a couple of marks! Really not very well thought out...

    Ahh well.

    I think I did them to 3 s.f.
    Who knows.

    Were we supposed to do them to the sig. figs. used in the question?
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    (Original post by TheTomD)
    Exactly!
    It didn't seem right at all. Part of the reason I felt so stumped was because of those questions that seemed simple, but were a couple of marks! Really not very well thought out...

    Ahh well.

    I think I did them to 3 s.f.
    Who knows.

    Were we supposed to do them to the sig. figs. used in the question?
    No idea at all mate, I had no idea what they were after for half the paper, so couldn't help you
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    (Original post by TheTomD)
    Exactly!
    It didn't seem right at all. Part of the reason I felt so stumped was because of those questions that seemed simple, but were a couple of marks! Really not very well thought out...

    Ahh well.

    I think I did them to 3 s.f.
    Who knows.

    Were we supposed to do them to the sig. figs. used in the question?
    i think i did them, so that they matched the other values in the question, so that the level of accuracy is the same. hope this is right! :confused:
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    (Original post by TheTomD)
    I honestly wasn't sure what that was asking for.
    First I started off talking about potential to kinetic energy, then (not thinking that was right...) went on to talk about the actual bow accelerating forward and contributing more energy.
    Pfft.

    I didn't enjoy that.
    I said about how the elastic potential energy in the string (caused by the tension) is converted to kinetic energy as it moves forward, is that right? :confused:
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    The question about showing x/L = sin theta, you had to find the angle for sin and then find the angle using the correct trig equations which is tan theta = opposite/ adjacent because we only had the opposite and adjacent values and sin theta is given by opposite/ hypotenuse. The angles were both 0.5729 or something so you could show it was a good approximation as the hypotenuse is almost the same length as the adjacent value because the angle is so small.

    Also, the question about the bow string was asking why the acceleration isn't constant as the arrow leaves the bow. I'm pretty sure you had to mention the fact that as the Bow is released the angle theta increases as does the Tension so the resultant force decreases. Then mention the fact that F=ma and the mass is constant, the acceleration must decrease.

    I didn't think the paper was too bad but there were a lot of wordy questions and that one about "show the lake could also have a standing wave of period 48 seconds" I couldn't think of anything decent to say for that one either.

    The thing I don't get about the OCR papers, they might have a suvat equation question for 1 mark and then a rearrange v=f*lambda question for 3 marks!? Doesn't seem very consistent.
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    (Original post by TheTomD)
    I feel exactly the same. Just seemed like a load of random non-sense that was just asking for you to 'Explain...'...'Explain...' etc.

    I also just thought that was what the question wanted...after about 5 minutes sat there thinking 'Okay...what am I supposed to be calculating again?!'

    But I did it. How many sig. figs did you use?

    Yeh I mean my worst part of physics is explaining stuff that is random examples of parts of the course, but on the whole I really like that about this course, it requires you to have a really good understanding of the concepts of physics, which in my opinion makes you much better at physics, as it's about thinking like a physicist.
 
 
 
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