OCR ADVANCING PHYSICS B G494 EXAM MONDAY 18th June

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    (Original post by jackofwack)
    For the question about the activation energy 'epsilon' in the fridge, was there any other way of doing it without having to solve two rather daunting simultaneous equations? I ended up dividing two equations and using Some indices work on the exponentials. It was however only 3 marks and uses a level of maths that some candidates won't have so what was the easier way? Unless I did it completely wrong ? (I got 1.6x10^-19 (or-18) or something by the way)
    yeah i did the same, that got rid of the constant, and after that i used log rules to split the horrible ln division, e's nicely cancelled out and i took a factor of epsilon out. divided through by (1/k288-1/k253) which gave 1.6x10^-19

    i do feel sorry for people that didn't take maths, that was a really harsh question :/
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    (Original post by Oromis263)
    I considered that as I walked out. I am pretty sure I got all the other technical terms in, but when I considered 3.4Hz I would agree that that is roughly the frequency at which you would bounce on a bumpy track.

    I would agree, but would hazard a guess that the boundaries will be similar to the January paper so roughly:

    54 - 100%
    49 - A*
    44 - A
    39 - B
    35 - C
    31 - D
    27 - E

    Perhaps?
    Need 80+ in this paper, so hoping they're slightly lower. They won't be much lower, mind, but the Hubble's constant may have thrown a few people, as was the disguised resonance question and the fridge question (which I must confess I got wrong, as in a moment of Further Maths induced stupidity forgot my power laws, and did (e^a)/(e^b) = e^(a/b) like a moron )

    So yes, I think your boundaries are probably correct, but shifted down two points each maybe... hopefully...
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    (Original post by Amy-Rose)
    Was stressing about the graph on the first page, couldn't decide between A and B! :')
    Is that the energy and voltage. ? If it is, it should be a quadratic graph E = 1/2CV^2. its Not E = QV because Q is not a constant


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    (Original post by Dhanu123)
    yeah i did the same, that got rid of the constant, and after that i used log rules to split the horrible ln division, e's nicely cancelled out and i took a factor of epsilon out. divided through by (1/k288-1/k253) which gave 1.6x10^-19

    i do feel sorry for people that didn't take maths, that was a really harsh question :/
    Yeah. Very true


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    I do A level maths and still couldn't do that epsilon question ----> :banghead::cry2: when I don't get my grade
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    (Original post by Oromis263)
    I considered that as I walked out. I am pretty sure I got all the other technical terms in, but when I considered 3.4Hz I would agree that that is roughly the frequency at which you would bounce on a bumpy track.

    I would agree, but would hazard a guess that the boundaries will be similar to the January paper so roughly:

    52 - 100%
    47 - A*
    42 - A
    37 - B
    33 - C
    29 - D
    25 - E

    Perhaps?
    I think/hope that seems better :p:
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    I thought the graph was C, because B was exponential but increasing, which only happens downwards when capacitors discharge. I thought it had to level off at the top but I'm probably wrong I got all of the other questions okay apart from that damn fridge question.
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    (Original post by hughh20)
    I thought the graph was C, because B was exponential but increasing, which only happens downwards when capacitors discharge. I thought it had to level off at the top but I'm probably wrong I got all of the other questions okay apart from that damn fridge question.
    It wasn't discharging though, it was storing energy, so it was B.
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    (Original post by Yarpie)
    It wasn't discharging though, it was storing energy, so it was B.
    Name:  capacitor_charge.png
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    This was the shape I meant, but I realise it was Energy and not Voltage on the Y axis. I wasn't sure how that'd change it so I put C, but I see where I went wrong with it
 
 
 
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