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    I found it pretty bad probly got around 70% .... I couldnt do the vector equation of the line of action of the force question nor the moments of inertia integration. I managed everything else and got the same answers as some mates tho....

    Any of these answers ring a bell? 39J, 77/109 sumthin..., 60 degrees?
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    EZ think i got 98%....syke...
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    any body got there soultions to print, i think i got all but the integration of that equilatral triangle lamina intergration ukno 7a, i made an stupid error. but for that vector equation for the line of action of R mine was something liek 4i - k or something like that, i have the paper if anybody wants a copy btw
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    (Original post by tktaylor6)
    i have the paper if anybody wants a copy btw
    Yes please! I have a few solutions. The rocket car question is exactly the same as Ex2A Q7 from the book, so i got the first part (bar a fudged negative) shame i ran out of time for the second part. :stupido2:
    The triangle integration I doubt many people will have got, I know I didn't. But the angle for that i don't think was 60° because G on an equliateral triangle is (1/√3)h from the vertex not (2/3)h :confused: correct me if i'm wrong.
    39J definitely sounds right.
    Any 2PI√(3a/8g) 's?
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    I thought because G is (1/√3)h horizontally from A and G is h/3 up along h from the base
    then
    AG squared = ((1/√3)h)^2 + (h/3)^2
    AG = 2h/3....
    I maybe wrong..... oh well method marks might save my ass....

    ps mackin_boi are you joking cos then UMS will bring me down........
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    (Original post by herman368)
    ps mackin_boi are you joking cos then UMS will bring me down........
    Yeah, if you have got that many marks it's a bit harsh on the rest of us, seeing as there are only about 300 people who take this paper. :p: good luck to you. Shall we stop worrying about that stupid triangle?
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    grrr that triangle, if i only i took my rod elements horizontally not vertically.....grrrrr

    oh well i put the most longwinded answer ever muhahahahahahahaa stupid examiners..
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    (Original post by herman368)
    I found it pretty bad probly got around 70% .... I couldnt do the vector equation of the line of action of the force question nor the moments of inertia integration. I managed everything else and got the same answers as some mates tho....

    Any of these answers ring a bell? 39J, 77/109 sumthin..., 60 degrees?

    ya i found THOSE questions to be REALLY hard, there are questions tht are easy, and others that are neither easy not hard, in general it was A LITTLE BIT hard, as those two questions are for 7 and 9 marks.



    the 39J is right
    77/109 I THINK it's something like that
    60 degrees, mmmmmmmm i remember having a pi/3 rad somewhere so i think u r right for that too...

    can anyone remember what the answers are? or questions too?
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    (Original post by yazan_l)
    in general it was A LITTLE BIT hard
    oh good, it wasn't just me! From your varing mass solution you seem pretty damn smart, so that's some encouragement.
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    well i got 39J also, and i used 2/3 h also dudes, ill scan this bad boy now and put it on here
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    i cant remeber which question but i think it was 4 b did anybody else get liek root with a root 2 inside that stuff beign rooted?
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    ok i dont know how to attach on this thing i have the paper so if your want a copy just add me onto msn its [email protected] and i will be happy to send it to you. also please share your answers with me after
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    (Original post by tktaylor6)
    i cant remeber which question but i think it was 4 b did anybody else get liek root with a root 2 inside that stuff beign rooted?
    YEAH, mate I got that...... also another guy at my school got that too!

    Phew...
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    hurrah!!!
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    Did any of you get that damned vector question? :mad: I had no idea how to approach it, so I complately made some stuff up in hopes of getting a couple of method (or sympathy!) marks.

    I got a 77/109 somewhere, 39J for work done, and I got a sqrt[2] inside a square root also - I believe it was for the period of the oscillations. The triangle one was definitely tricky, as there were parallel and perpendicular axes involved (took me a while to notice that).

    I made a load of stupid mistakes too, e.g. 1-0.5=0.25, so my answer to the angle question was arccos(0.25) instead of arccos(0.5)=pi/3. And for the vertical component question I went and found the horizontal component. Ugh.

    Also, how did you guys do the last part of the last question - the maximum angular acceleration one? I tried using L = I \ddot{\theta}, but for some reason I changed my mind and went and found the minimum tangential acceleration instead. No idea why I did that, although I like to blame exam pressure.

    I feel like crap now.
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    (Original post by dvs)
    Did any of you get that damned vector question?
    Here's what I did, it may be right may be wrong:

    xi+yj+zk x R = G

    | i j k |
    | x y z | = 7i-3j+8k
    |-1 3 2|

    equating components of i, j and k:
    2y-3z = 7
    -(2x+z) = -3
    3x+y = 8

    letting x=0 : y=8, z=3

    line of action is therefore
    r = 8j+3k +k(-i+3j+2k)
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    Hmm.. But why should R be parallel to G?
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    (Original post by Daft Wader)
    Here's what I did, it may be right may be wrong:

    xi+yj+zk x R = G

    | i j k |
    | x y z | = 7i-3j+8k
    |-1 3 2|

    equating components of i, j and k:
    2y-3z = 7
    -(2x+z) = -3
    3x+y = 8

    letting x=0 : y=8, z=3

    line of action is therefore
    r = 8j+3k +k(-i+3j+2k)

    are you sure of this?
    i mean i dont know and i hope so, coz i did all to :
    2y-3z = 7
    -(2x+z) = -3
    3x+y = 8
    and then stopped because i thought it was all wrong!!! i HOPE u are right!!! but DAMN IT, why i didnt continue!!!! :mad:
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    (Original post by Daft Wader)
    oh good, it wasn't just me! From your varing mass solution you seem pretty damn smart, so that's some encouragement.

    lol thanks , hehehe, cheers
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    by the way: for the pendulum period question, which should be used:
    T = 2π √[I/(mgh)] OR T = 2π/w?
 
 
 
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