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    (Original post by QuantumStuff)
    I used V = u + at to work out the Velocity at t=3. Then used pythagoras to work out speed.

    Does that sound okay?
    Mhm. I That's what my expanation is. That very equation. where u is the velocity at t=0 and at is the change in velocity/
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    (Original post by Don Pedro K.)
    Does it matter if you worked out M before d?
    nah
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    (Original post by jamessmith15)
    can someone explain to me how i got root 5 over 2 twice for 7a instead of 2.5i and 2.5j and how many method marks would i have got.
    Also i got 0.2 for the impulse question as forgot to change signs form 3.5 to -3.5. How many would i loose here, I'm thinking min 2 or max 3
    Here is the method, see where you think you went wrong:

    F1 = - i + 2j,
    F2 = k(i + j) [Note it was in the direction of i + j, not equal to it]
    Resultant F = m(i + 3j) [Again direction of i + 3j]

    Resultant F = F1 + F2
    = - i + 2j + k(i + j)
    = (k-1)i + (k+2)j

    k-1 = m --- equation 1
    k+2 = 3m --- equation 2.
    equation 1 x 3 => 3k - 3 = 3m.
    3k - 3 = k + 2
    2k = 5
    k = 2.5

    F2 = k(i + j) = 2.5(i + j) = 2.5i + 2.5j
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    (Original post by kapisz)
    can someone show q7 a working out?

    and if u got d=1.6 and M=66 due to using wrong distance but working correct how many marks would i get?
    Yeah i'll do it on paper and send it
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    Wow, for the first question I got 640i+640j, then crossed it out , for the moments one I got 180kg and 3.5 as the distance , For the pulley one I all of it, but I put the direction as a bearing of 045 degrees , The collisions one I found the acceleration, but must've substituted it back in wrong! All of the other questions I got right (I think), but just two quick questions:

    1. How many marks would I get for the collisions if I found the acceleration correctly (1.225) but subbed in wrong
    2. Does anyone know what 53 - 55 marks would be as a grade?
    Thanks :P
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    (Original post by txnilxnur)
    Your acceleration is wrong.. its
    (-0.4*g*1/8) divided by 0.4 which gave a=-1.225
    Thank god you got the same acceleration as me
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    Alright, time to leave this thread haha! Best just to forget about it now and focus on the other exams; what happens will happen Good luck everyone, let's smash C3 and C4!!
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    (Original post by Economistician)
    Anyone mind giving their opinion on a quick question...

    For 7b.) With the vector of velocity (3i - 22j) and acceleration of (3i + 9j) i think it was.

    I done it right and got 13, but then i stupidly crossed it out and found the magnitude of the velocity (√493) and magnitude of the acceleration (3√10). And so after 3 seconds of acceleration, i got √493 + 9√10 = 50.7 ms-1.

    Do you think i will get 0 marks? I'm thinking yes...
    Also, does anyone know how many marks 7b was worth?

    Any replies are appreciated
    Anyone?
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    what was the answer to 5, i got mew = 0.93? but i think its wrong
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    (Original post by SirRaza97)
    That's savage. I hate this type of stuff. I'd rather have an accurate answer than a rounded one.
    correction, you can only be penalised once for this throughout the whole paper so don't fret

    note I was told this by a friend so might not be right :rolleyes::rolleyes:
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    (Original post by Economistician)
    Anyone?
    i also got that answer
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    guys does anyone remember the details of question 6 and 7 so i can upload model answers?
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    (Original post by Buziel)
    Wow, for the first question I got 640i+640j, then crossed it out , for the moments one I got 180kg and 3.5 as the distance , For the pulley one I all of it, but I put the direction as a bearing of 045 degrees , The collisions one I found the acceleration, but must've substituted it back in wrong! All of the other questions I got right (I think), but just two quick questions:

    1. How many marks would I get for the collisions if I found the acceleration correctly (1.225) but subbed in wrong
    2. Does anyone know what 53 - 55 marks would be as a grade?
    Thanks :P
    Aww sorry to hear about a few silly mistakes, I'd imagine 53-55 marks is high B territory if the grade boundaries are similar to previous years. From memory the impulse questions was 7 marks so getting the acceleration should give you 4 ish and perhaps if the correct method was used could end up getting 5 overall, sadly this is just speculation based on nothing but past mark schemes. Hope that helps
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    if u got d=1.6 and M=66 due to using wrong distance but working correct how many marks would i get?
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    (Original post by RedDevil1997)
    Will I get the mark for saying the direction of the force on the pully is Southwest??
    Don't know if any one has responded to you, but I am not sure what they meant, because I agree with you but I just wrote towards the table...I am sure they will give us the mark
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    (Original post by KloppOClock)
    guys does anyone remember the details of question 6 and 7 so i can upload model answers?
    Yup, question six was the moments: mass of non uniform rod 30kg, two supports ST, AS = 0.5, TB = 2, whole length is 6m.

    If mass of Mkg is placed at B, it is on the point of tipping about S
    If mass of Mkg is placed at A, it is on the point of tipping about T.
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    (Original post by kapisz)
    can someone show q7 a working out?

    and if u got d=1.6 and M=66 due to using wrong distance but working correct how many marks would i get?
    I put AS = d but I meant A to centre of mass = d




    Here you go. This is how I did it.
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    why do they put vectors at q1 scares the hell out of me
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    Although you may get marks for expressing your answer for the direction of the force in Q7 as a bearing, the concept makes no sense.

    The diagram concerns a vertical plane. The force is diagonally downwards. All compass directions including bearings are horizontal. So don't mock your friends because they didn't give a bearing, they are the sensible ones.
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    (Original post by ZoeAlison97)
    correction, you can only be penalised once for this throughout the whole paper so don't fret

    note I was told this by a friend so might not be right :rolleyes::rolleyes:
    Your questions are marked separately, so noone sees the whole paper. It may be decided that the 3 or 2 s.f. rule is only applied on one particular question, or it may not, in which case you'll lose one per question.
 
 
 
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