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M1 Vectors Question Watch

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    I've attached the question I'm struggling with. I've understood everything, except part d.

    I know why there's no i component, but I'm having trouble with why they're using the 9-2t=0 part.

    Name:  ImageUploadedByStudent Room1453560182.063260.jpg
Views: 90
Size:  77.4 KB


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    (Original post by meloj)
    I've attached the question I'm struggling with. I've understood everything, except part d.

    I know why there's no i component, but I'm having trouble with why they're using the 9-2t=0 part.

    Name:  ImageUploadedByStudent Room1453560182.063260.jpg
Views: 90
Size:  77.4 KB


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    If (9-2t)\boldsymbol{i} + (-9+4t)\boldsymbol{j} has no \boldsymbol{i} component then (9-2t) must be equal to 0.
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    (Original post by notnek)
    If (9-2t)\boldsymbol{i} + (-9+4t)\boldsymbol{j} has no \boldsymbol{i} component then (9-2t) must be equal to 0.
    How come the answer from part b ie. the vector AB is used? I'm confused why you couldn't just use the actual position of A.

    Thanks for your help!


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    (Original post by meloj)
    How come the answer from part b ie. the vector AB is used? I'm confused why you couldn't just use the actual position of A.

    Thanks for your help!


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    Draw two points A and B where A is north of B on a set of axes. The position vector of A is the vector that goes from the origin to A. This vector could be any direction.

    But the vector from A to B is the one that must be vertical i.e. have no \boldsymbol{i} component.

    And to work out the vector AB, you subtract the vector OA from the vector OB.

    If you're still unsure, please let me know the exact part of this explanantion that doesn't make sense.
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    (Original post by notnek)
    Draw two points A and B where A is north of B on a set of axes. The position vector of A is the vector that goes from the origin to A. This vector could be any direction.

    But the vector from A to B is the one that must be vertical i.e. have no \boldsymbol{i} component.

    And to work out the vector AB, you subtract the vector OA from the vector OB.

    If you're still unsure, please let me know the exact part of this explanantion that doesn't make sense.
    I think I'm okay with it now. Thank you so much for your help, vectors really are a pain to understand sometimes!


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    Name:  1453589021284.jpg
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Size:  34.8 KBName:  1453589075663.jpg
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Size:  29.2 KB hey, I have a similar question, please tell me where I went wrong in part (c), the answer is 6.5

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    What is wrong with the labels these days?
    New trend?
    Why does this show as a Y9? A system bug?
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    (Original post by TeeEm)
    What is wrong with the labels these days?
    New trend?
    Why does this show as a Y9? A system bug?
    Yeah I've noticed that too. Seems like too many to be a coincidence.
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    (Original post by TeeEm)
    What is wrong with the labels these days?
    New trend?
    Why does this show as a Y9? A system bug?
    Well, can you help me with the above question ?

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    (Original post by PlayerBB)
    Well, can you help me with the above question ?

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    (Original post by notnek)
    Yeah I've noticed that too. Seems like too many to be a coincidence.
    i am a bit busy updating my site at present
    @notnek I am sure can help you with this question
    all the best (sorry)
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    (Original post by PlayerBB)
    Well, can you help me with the above question ?

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    Try substituting t=2 into the position vector and then draw it. Is that north-west?

    Then think about how you can correct it.
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    (Original post by notnek)
    Try substituting t=2 into the position vector and then draw it. Is that north-west?

    Then think about how you can correct it.
    OH!! Thank you , one last question when they give me a question like this, how can I immediately know if the / is negative before trying out and then figuring the right answer?

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    @TeeEm It's okay and thank you anyway

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    (Original post by PlayerBB)
    OH!! Thank you , one last question when they give me a question like this, how can I immediately know if the / is negative before trying out and then figuring the right answer?

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    Nvm I knew it and thank you!!

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    (Original post by PlayerBB)
    Nvm I knew it and thank you!!

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    Thanking youself is the first sign of madness.
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    (Original post by notnek)
    Thanking youself is the first sign of madness.
    Lol I meant it for you and don't worry I am not mad, I am just sleepy :/

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