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AQA Physics PHYA4 - Thursday 11th June 2015 [Exam Discussion Thread] Watch

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    (Original post by DanielWall96)
    didnt it turn 90 degrees in 0.5 seconds
    I think so... So that's angular alright
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    Is there an UNNOFICIAL Ms?
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    (Original post by Sbarron)
    I think so... So that's angular alright
    I doubled it for angular of a whole period though?
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    (Original post by StarvingAutist)
    Damping affects the amplitude too.

    The formula sheet equations assume no air resistance. The mass of the bob has an effect on that.
    Did it mention air resistance in the question? they can't be that harsh
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    Hey guys!

    My physics teacher has got back to me!

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    (Original post by NEWT0N)
    Thanks yes I remember doing something like that. Do you remember the velocity? I think 8.6ms^-1
    I think I got half that... Not sure though I can't remember much at all
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    (Original post by Kkdhaliwal)
    Is there an unofficial Ms up?
    Not unfortunately. But the paper comes in about ten days(not like the EMPA though as the examiners are not releasing the EMPA's for some strange reasons). Once we have the paper, the mark scheme is not a problem.


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    (Original post by CD223)
    Hey guys!

    My physics teacher has got back to me!

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    Yeah I hope it's dropped and they reduce the grade boundaries by 3 marks for the wasted time and extra stress lol
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    (Original post by NEWT0N)
    Thanks. Thing is I'm just completely blank about what I did but I'm fairly sure I didn't get 2 now. I remember being given a speed, maybe I used the speed from a previous question or something silly like that. How many marks was it?
    Only 2 marks


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    (Original post by jgarnham)
    Why are you going slower with the larger mass? The time period is the same is it not as it is independent of the mass of the bob?
    NEWTON is not quite right. He's suggesting you add mass to the pendulum while it is oscillating, which is not correct.

    The reason is that the force that causes the damping is equal for both cones. As we know from F=ma (or rate of change of momentum), a force has a larger effect on an object with a lower mass. The reduction in momentum due to the damping force is the same, but the reduction in velocity is smaller for the larger mass (i.e. with the ring), meaning the reduction in kinetic energy (and thus total energy) is lower, and therefore the damping is less with a higher mass.
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    (Original post by StarvingAutist)
    Damping affects the amplitude too.

    The formula sheet equations assume no air resistance. The mass of the bob has an effect on that.
    You're saying the reason it dampens is because it adds air resistance? That's pretty weak reasoning if you ask me. If they wanted an answer about air resistance they would've made it more obvious.

    They mentioned no dimensions when they were talking about the ring. Theoretically you could have an EXTREMELY small volume ring with a massive density which would mean the extra air resistance is negligible.

    I'm still gonna go with no change on the damping.
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    (Original post by NEWT0N)
    Great, so the whole question would get dropped?

    Slightly unfair on people who got the rest of that question right though, because people who didn't would essentially be getting away
    what question is this??
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    what did everyone get for the emf
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    (Original post by NEWT0N)
    Great, so the whole question would get dropped?

    Slightly unfair on people who got the rest of that question right though, because people who didn't would essentially be getting away
    Well I doubt they'll get off because it doesn't mean they'll lower grade boundaries as a ratio to the rest of the paper from what it would have been including the marks if you get what I mean.... I think they'll just forget it even existed rather than essentially give everyone three extra marks
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    legend!!
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    How do you guys remember the paper in so much detail!? I've forgotten half of it already! But how the **** were you supposed to get a full six points in on the long one? I'm not sure I've ever got 6 marks on a 6 mark question, EVER!
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    (Original post by NEWT0N)
    Great, so the whole question would get dropped?

    Slightly unfair on people who got the rest of that question right though, because people who didn't would essentially be getting away
    Only the 3 marks for the graph would be dropped, not the whole question
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    (Original post by ajcoo)
    How do you guys remember the paper in so much detail!? I've forgotten half of it already! But how the **** were you supposed to get a full six points in on the long one? I'm not sure I've ever got 6 marks on a 6 mark question, EVER!
    You will probably forget the other half by 12:00


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    I know this is a long shot, but can anybody remember the questions with their corresponding marks (just briefly). I'm not asking for answers or anything, I just wanna mentally calculate where I think I might have gained marks (praaaaaying I get the C I need!)
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    (Original post by chizz1889)
    That gives you change in potential so you have to multiply by 60*10^-9 and no as work is done by the particle which is what it asked

    Why are you using the 30nC and not the 60nC charge? I know most people got an answer around 4.5 x 1^(k) (dont remember the power) but i got the double of that answer.

    I used 60nC/4pie0 (5-2) rather than 30nC/4pie (5-2)

    Then times it by the 60nC charge to find work done.
 
 
 
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