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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)
    Humm, I used the same method, but I made it equal to the SUM of the couple caused by teh two forces AND the one given in the question, so it wasn't = 7i-3j+8k... hummm

    My answers where:

    1. 39 J

    2. r = 3je^-t + (2i - 4j)e^-2t

    3. a) -i + 3j + 2k
    b) r = i + 9j + 4k + λ(-i + 3j + 2k) (probs wrong, though)

    4. a) Proved it, though it sounded VERY VERY easy for seven marks - just quoted things from formula book and too me four lines. Think I did smthing wrong
    b) 11ω/19

    5. a) 7mg/4
    b) 2 Pi * √( 81 / 3g√2) - that's very obviously wrong, though !

    6. a) Proved
    b) Tried, but couldn't do it

    7. a) Used integration, but got the wrong answer
    b) angel = 18.38 degrees (wrong, I think)
    c) Ran out of time
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    (Original post by danguetta)
    Humm, I used the same method, but I made it equal to the SUM of the couple caused by teh two forces AND the one given in the question, so it wasn't = 7i-3j+8k... hummm

    My answers where:

    1. 39 J

    2. r = 3je^-t + (2i - 4j)e^-2t

    3. a) -i + 3j + 2k
    b) r = i + 9j + 4k + λ(-i + 3j + 2k) (probs wrong, though)

    4. a) Proved it, though it sounded VERY VERY easy for seven marks - just quoted things from formula book and too me four lines. Think I did smthing wrong
    b) 11ω/19

    5. a) 7mg/4
    b) 2 Pi * √( 81 / 3g√2) - that's very obviously wrong, though !

    6. a) Proved
    b) Tried, but couldn't do it

    7. a) Used integration, but got the wrong answer
    b) angel = 18.38 degrees (wrong, I think)
    c) Ran out of time
    I agree with 1,2,3a,5a.... ur 5b has a square root in a root so its similar to mine.... i disagree with ur 3b 4b and 7a
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    i think the angle was 60 degree's also the lien of action i got the value like you guys did that was like 4j -k or something liek that but i left it as that i didnt times that by lamda and add the force, isnt the line of force the direction its acting...? apart from that i did everything
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    (Original post by danguetta)

    4. a) Proved it, though it sounded VERY VERY easy for seven marks - just quoted things from formula book and too me four lines. Think I did smthing wrong
    b) 11ω/19
    sorry but part b is wrong:
    it's 77w/109
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    (Original post by yazan_l)
    by the way: for the pendulum period question, which should be used:
    T = 2π √[I/(mgh)] OR T = 2π/w?
    The only time I've seen it make a difference is when they specify which to use on the paper, eg. "by considering the equation of motion..." They didn't specify so it shouldn't matter. I did T = 2π/w, with w²=(8g/3h) or something like that, and got the same answer as everyone else at my centre.
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    (Original post by Daft Wader)
    The only time I've seen it make a difference is when they specify which to use on the paper, eg. "by considering the equation of motion..." They didn't specify so it shouldn't matter. I did T = 2π/w, with w²=(8g/3h) or something like that, and got the same answer as everyone else at my centre.
    well actually i think that i had a calculating mistake or something ( i used T = 2pi rt[I/mgh]), so i didnt have the same answer when i used the T = 2π/w method.
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    Do you guys reckon that 60/75 will be an A this year?
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    (Original post by herman368)
    Do you guys reckon that 60/75 will be an A this year?

    oh i hope it's even LESS!!!
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    (Original post by herman368)

    ps mackin_boi are you joking cos then UMS will bring me down........

    dont worry, mackin boi strugled with M2 and doesnt even do furthur maths...hes just having a laugh
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    (Original post by yoyo12345)
    dont worry, mackin boi strugled with M2 and doesnt even do furthur maths...hes just having a laugh
    o thank god.... i figured cos he didnt cross it off in his sig
 
 
 
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