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    (Original post by n2697)
    I NEED HELP WITH QUESTION 6 :https://3b0a7b1bc87f5381e60f8f717510...%20Edexcel.pdf
    It says to find the greatest possible value of x - and in order to do that you take moments about B and assume the reaction force at A is 0 - but WHY?!

    Imagine if the particle was all the way at the end at point C. The forces would be unbalanced and the rod would tip around the point B. Now imagine the particle is in the centre, the rod would remain in equilibrium. This means that the further away X is, the lower the reaction at A is. So what the question is asking you is to find the furthest value of X before the rod tips over. Now in order to this, you need to know this fact.


    When X is the furthest away it can be before the rod tips, the value of the reaction at A must be 0.

    You can then use that to take moments about B and solve the question.

    Here is a more clearer explanation:
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    (Original post by Zacken)
    lol srs? I haven't even done one paper in the past three days. :rofl:
    Dude you're the kind of guy who could self teach M4 in 45 minutes so I'm not even gonna compare myself to you 😜


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    Hi
    Can someone help me with why the impulse for part B is 2100 and not 2700 ?
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    (Original post by Marccs)
    Hi
    Can someone help me with why the impulse for part B is 2100 and not 2700 ?
    Can you post working to show how you got 2700?
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    (Original post by notnek)
    Can you post working to show how you got 2700?
    I was doing it again to post the working and then I got the right answer , it was a sign change mistake
    Thanks
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    I have no clue how to find parallel vectors. Could someone help me out with the b) part ?


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    (Original post by Steph.shakes)
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    I have no clue how to find parallel vectors. Could someone help me out with the b) part ?


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    can you tell me what paper it is?
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    (Original post by Steph.shakes)
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    I have no clue how to find parallel vectors. Could someone help me out with the b) part ?


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    Here:

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    (Original post by Kawaii289)
    can you tell me what paper it is?
    It's January 2014


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    (Original post by KloppOClock)
    Here:

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    Thank you very much. It was very helpful


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    (Original post by Steph.shakes)
    Thank you very much. It was very helpful


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    no problem
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    Hi
    Can anyone help me with this vectors question
    The whole question is quite confusing
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    (Original post by Marccs)
    Hi
    Can anyone help me with this vectors question
    The whole question is quite confusing
    Is this from an official paper?
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    (Original post by KloppOClock)
    Is this from an official paper?
    Yes June 2001
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    (Original post by Marccs)
    Hi
    Can anyone help me with this vectors question
    The whole question is quite confusing
    a) 6i + 8j
    If he is on the pipe he must have an i value of 6. If he the radio tower is SW of him, the j value between him and the mast is the same as the i value between him and the mast. The tower is at (0i + 2j) and he is at (6i + xj) --> the i difference is 6 so the j difference is 6 as well, meaning he has a j value of 8

    b) His distance from the origin is route(6^2 + 8^2) (pythag) which is 10km. If they're travelling at 5km/h, it'll take 2 hours.

    c) 6i - 4j
    Same logic as a)

    Didn't try d) because idk if I've got this right

    Edit: fixed typo
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    (Original post by neon_reaper)
    a) 6i + 8j
    If he is on the pipe he must have an i value of 6. If he the radio tower is SW of him, the j value between him and the mast is the same as the i value between him and the mast. The tower is at (0i + 2j) and he is at (6i + xj) --> the i difference is 6 so the j difference is 6 as well, meaning he has a j value of 8

    b) His distance from the origin is route(6^2 + 8^2) (pythag) which is 10km. If they're travelling at 5km/h, it'll take 2 hours.

    c) 6i - 4j
    Same logic as a)

    Didn't try d) because idk if I've got this right

    Edit: fixed typo
    For all North West and South West etc is it the difference of i components and j components , or is there a negative sign needed?
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    (Original post by Marccs)
    For all North West and South West etc is it the difference of i components and j components , or is there a negative sign needed?
    Kind of both, it depends which direction you're going. If you think about it on a graph, North is positive (+j), West is positive (+i), South is negative (-j), and East is negative (-i).

    So say O is (0,0) and P is (x, 5), and P is directly NW of O. The j difference is 5 so the i difference is 5 as well and because W is positive, its 5i.

    If P were NE of O, the i difference is still 5 but because E is negative, its -5i.
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    (Original post by neon_reaper)
    Kind of both, it depends which direction you're going. If you think about it on a graph, North is positive (+j), West is positive (+i), South is negative (-j), and East is negative (-i).

    So say O is (0,0) and P is (x, 5), and P is directly NW of O. The j difference is 5 so the i difference is 5 as well and because W is positive, its 5i.

    If P were NE of O, the i difference is still 5 but because E is negative, its -5i.
    So taking N is J and E is I
    NE : +J +i
    SE: -J + i
    SW: -J -i
    NW: +J-i

    So why for part a were it was SW we took both i and j as +ve
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    (Original post by Marccs)
    So taking N is J and E is I
    NE : +J +i
    SE: -J + i
    SW: -J -i
    NW: +J-i

    So why for part a were it was SW we took both i and j as +ve
    Because if the mast was SW of the man, he was NW of the mast.
    Alternatively you could have done man(6i + xj), mast(0i + 2j).
    The difference is -6 on both i and j because the mast is SW, so
    (i) 6-6=0 and (j) x-6=2

    I find it helps to draw it on a graph
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    (Original post by neon_reaper)
    Because if the mast was SW of the man, he was NW of the mast.
    Alternatively you could have done man(6i + xj), mast(0i + 2j).
    The difference is -6 on both i and j because the mast is SW, so
    (i) 6-6=0 and (j) x-6=2

    I find it helps to draw it on a graph
    Thank You I just understood it now
 
 
 
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