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    (Original post by Marxist)
    m=42 and d=1.2
    what were the units for 42 i think wrote it as in newtons?
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    Like many people, I thought the force exerted by the brick was just 1.5g / 14.7N. It was a 3 mark question; would I get any marks, or 0/3?

    (Original post by Don Pedro K.)
    I didn't get impulse as -3Ns initially? I just got it as 3Ns from the get go
    It depends which direction you take to be positive but it could also be because you mistakenly did m(u-v) instead of m(v-u) (or mu-mv instead of mv-mu). If it's the latter, you technically did it wrong but I don't know whether you'd lose marks or not.
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    (Original post by matt1234512)
    what were the units for 42 i think wrote it as in newtons?
    It was the mass which would be in kilograms, however it said find the value so units weren't really required
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    KloppOClock hogree Guys for the F2 vectors question, I realised at the last minute how to do it so I had to rush it. I got the two sets of simultaneous equations, but then solved them wrongly. How many marks out of 7 do you reckon I'll get? 4?
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    (Original post by JLegion)
    d = 1.2 and M = 42, which seems to be the general consensus.

    How did you do it? Given my method took up 2 sides, I imagine yours was much quicker.
    Yh my answers are wrong.
    M(p) (30g *(d-0.5)) = (Mg *0.5)
    M(q) (30g * (4-d)) = (mg *2)

    I ended up getting d=1
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    Anyone remember how many marks the moments question was worth?

    I took moments for both pivots but put the wrong value for distance in one of them. I solved it but my answers were wrong due to the mistake?

    Any idea how many marks I would have lost?
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    For the moments question I got 42.something and 1.2something for the distance, was the answers exactly those or am I right
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    (Original post by the_chosen_one97)
    I got d=1.2 and M=42 which I have heard from a few people is the correct answer
    (Original post by vvlp)
    d=1.2M=42
    👍

    (Original post by txnilxnur)
    I got that too.. but I think we went wrong by doing the distances wrong.. I think what I did was do the COM times the distance from A but it was supposed to be from the pivot!
    Not sure about you but I'm sure thats what i did wrong

    EDIT- just realised I did times by the right distances so not actually sure where I went wrong.. can someone explain?
    That's what I thought might have happened but then I saw your edit and was pretty sure I multiplied by the right distances, I did check though
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    (Original post by txnilxnur)
    I got that too.. but I think we went wrong by doing the distances wrong.. I think what I did was do the COM times the distance from A but it was supposed to be from the pivot!
    Not sure about you but I'm sure thats what i did wrong

    EDIT- just realised I did times by the right distances so not actually sure where I went wrong.. can someone explain?
    i got that at first. u have multiplied the COM in the second scenario by (6-d) and it should be (4-d).
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    (Original post by Ashelly)
    Yh my answers are wrong.
    M(p) (30g *(d-0.5)) = (Mg *0.5)
    M(q) (30g * (4-d)) = (mg *2)

    I ended up getting d=1
    Hey, the majority (and me) have been wrong many times before.
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    can someone explain the Vectors F2 question please?
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    On the impulse question, I made a stupid mistake and forgot to sub in 'g' when calculating Fmax, but I did everything else right. How many marks would I lose for this??
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    (Original post by jtmass22)
    i got that at first. u have multiplied the COM in the second scenario by (6-d) and it should be (4-d).
    Damn... know how many marks we would have lost for doing that? I was aiming for 100ums but I've already waved goodbye to that...
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    (Original post by JLegion)
    Hey, the majority (and me) have been wrong many times before.
    That moments question was the exact replica of the moments question (ques 6) in the june 2013 paper. I did my answer similar to that mark scheme.
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    how were you meant to do 7a
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    Quick question hoping someone can clear this out
    1) for the first question I got got 14 soemthjng degrees and I mentioned this is from the positive X AXIS or to the right
    People seem to have done 90+ this to get from y axis but they didn't mention so I just used X axis

    2) for the coefficient of friction I got the right answer but it came out negative because I took the friction pointing UP the slope and someone said it was down the slope
    How much would I lose out I think it was 10 marks ?
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    (Original post by thestarter)
    can someone explain the Vectors F2 question please?
    F2 in the direction of (i+j) so F2 = k(i+j)
    Where k is some constant to be found.

    We're also told the resultant force, R, is in the direction (i -3j) <---- Not sure about the numbers there.
    So R = z(i-3j), where z is some constant.

    Equate components, I.e. F1 i components + F2 i components = R i components

    Do the same for j.
    Achieve two equations in terms of k and z, solve simultaneously for k.

    I don't think you have to calculate the magnitude for this one, but if you did, so long as you wrote it in vector form you should still get full marks.
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    (Original post by jtmass22)
    i got that at first. u have multiplied the COM in the second scenario by (6-d) and it should be (4-d).
    yeah I just did the question again and put (6-d)!! Such a stupid mistake... how many marks do you think I will lose? The equation for moments about S was right though!
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    (Original post by JLegion)
    F2 in the direction of (i+j) so F2 = k(i+j)
    Where k is some constant to be found.

    We're also told the resultant force, R, is in the direction (i -3j) <---- Not sure about the numbers there.
    So R = z(i-3j), where z is some constant.

    Equate components, I.e. F1 i components + F2 i components = R i components

    Do the same for j.
    Achieve two equations in terms of k and z, solve simultaneously for k.

    I don't think you have to calculate the magnitude for this one, but if you did, so long as you wrote it in vector form you should still get full marks.
    What was the vector F1, i always seem to get F2=0.5i+0.5j
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    Guys, for the magnitude of the force exerted on pan by brick, I got the right answer but I did it in a way which gave a negative answer for R. how many marks do you think I would lose?
 
 
 
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