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    (Original post by buckeybarnes)
    how do you know whether constant of integration =0 when you're integrating the equation if you're doing an SVA question?
    Hi. When you integrate, you use a set of values you know from the information given/ you worked out to get the constant.
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    (Original post by MsFahima)
    Hi. When you integrate, you use a set of values you know from the information given/ you worked out to get the constant.
    Hey

    Do you mind helping me with the last part of the last question . 7iv.

    Thanks
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    (Original post by Super199)
    Hey

    Do you mind helping me with the last part of the last question . 7iv.

    Thanks
    Which paper?
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    (Original post by Lilli1997)
    Attachment 421361

    Pic might be sideways. Hope it makes sense!
    thank you!
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    Yo guys, does anyone have any useful info/technique for pulleys/friction/rough inclined planes. When are we meant to use F-f=ma? I'm finding core 3 and core 4 much easier than m1 as I've done a tonne of it (and I really want that A*), but am really bad at m1 (barely scraping b's/low a's). Any advice on how to approach tonight/tommorrow for revision on these topics. Thanks
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    (Original post by MsFahima)
    Which paper?
    June 08 sorry
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    (Original post by Sonnyjimisgod)
    Yo guys, does anyone have any useful info/technique for pulleys/friction/rough inclined planes. When are we meant to use F-f=ma? I'm finding core 3 and core 4 much easier than m1 as I've done a tonne of it (and I really want that A*), but am really bad at m1 (barely scraping b's/low a's). Any advice on how to approach tonight/tommorrow for revision on these topics. Thanks
    Yeah same haha. C3/C4 is a lot better haha
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    (Original post by Super199)
    June 08 sorry
    Working on it!
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    (Original post by MsFahima)
    I'm struggling with Q5 ii) unfortunatley. For Q5)i) The area under the graph is the displacement so we can work that out easily. (3*20)/2 = 30.

    I'll tag kawehi to help you out. I'm sorry!
    Do you guys still need help with this? Sorry for the late reply, I've been out all day
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    (Original post by kawehi)
    Do you guys still need help with this? Sorry for the late reply, I've been out all day
    Yes please!
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    (Original post by Super199)
    June 08 sorry
    So for the first part. Show that Q travels at a constant speed.. if a=0 then that shows v is constant. For this, we do f = ma just for Particle Q. So f = ma down the plane gives us: -Fr + 0.2gSin(45) = 0.2a. Fr is 1.386 and 0.2gSin(45) is 1.386.

    -1.386 + 1.386 = 0.

    0=0.2a

    therefore a = 0.

    Attachment 421709

    Next part:

    Name:  1433702228155.jpg
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Size:  52.2 KB


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    (Original post by buckeybarnes)
    thanks
    (Original post by MsFahima)
    I'm struggling with Q5 ii) unfortunatley. For Q5)i) The area under the graph is the displacement so we can work that out easily. (3*20)/2 = 30.

    I'll tag kawehi to help you out. I'm sorry!

    Ok, so I'm guessing that you guys got the first part, and found that the first triangle was = 30?

    So, since the lorry is leaving from one spot, then returning to that same spot after a little journey, you know that the total displacement has to equal zero. This means that you can set the 2 triangles (one of them is vaguely parallelogram-y, but it's not too bad to work out) equal to eachother!

    We found the first one already, so we've got half of the equation done.

    30=

    Now for the slightly more tricky bit:
    Name:  4m1.PNG
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    The q says that the lorry accelerates up to v=3, then remains at v=3 for 4 seconds, then decelerates back down to v=0, where it has returned to the weighbridge or whatever.

    This means that you know the flat bit of the parallelogram. I've labelled it on that diagram! It's just a rectangle of 3x4.

    Now we have the 2 chunks of area on either side of that rectangle. We can just pretend that the rectangle in the middle doesn't exist, and then suddenly you just have a triangle that's base = t and h = 3.

    So we can sew it all together to get:

    30 = 3*4 + (1/2)*3*t
    t=12

    To get the total time elapsed, we already have the t=60 that was given on the diagram, so it's just a matter of adding 4 and t to that, giving 76.

    PS, can't be bothered to find the mark scheme rn, so just assuming this is right haha

    Do you need help with part iii) too?
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    (Original post by kawehi)
    Ok, so I'm guessing that you guys got the first part, and found that the first triangle was = 30?

    So, since the lorry is leaving from one spot, then returning to that same spot after a little journey, you know that the total displacement has to equal zero. This means that you can set the 2 triangles (one of them is vaguely parallelogram-y, but it's not too bad to work out) equal to eachother!

    We found the first one already, so we've got half of the equation done.

    30=

    Now for the slightly more tricky bit:
    Name:  4m1.PNG
Views: 74
Size:  9.3 KB
    The q says that the lorry accelerates up to v=3, then remains at v=3 for 4 seconds, then decelerates back down to v=0, where it has returned to the weighbridge or whatever.

    This means that you know the flat bit of the parallelogram. I've labelled it on that diagram! It's just a rectangle of 3x4.

    Now we have the 2 chunks of area on either side of that rectangle. We can just pretend that the rectangle in the middle doesn't exist, and then suddenly you just have a triangle that's base = t and h = 3.

    So we can sew it all together to get:

    30 = 3*4 + (1/2)*3*t
    t=12

    To get the total time elapsed, we already have the t=60 that was given on the diagram, so it's just a matter of adding 4 and t to that, giving 76.

    PS, can't be bothered to find the mark scheme rn, so just assuming this is right haha

    Do you need help with part iii) too?
    Thank you very much. I forgot that the displacement has to equal zero. Thanks again!

    PRSOM
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    (Original post by MsFahima)
    Thank you very much. I forgot that the displacement has to equal zero. Thanks again!

    PRSOM
    No problem haha
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    (Original post by Sonnyjimisgod)
    Yo guys, does anyone have any useful info/technique for pulleys/friction/rough inclined planes. When are we meant to use F-f=ma? I'm finding core 3 and core 4 much easier than m1 as I've done a tonne of it (and I really want that A*), but am really bad at m1 (barely scraping b's/low a's). Any advice on how to approach tonight/tommorrow for revision on these topics. Thanks
    I'm assiming for many of us this is the last exam. It may be good tomorrow to do a group online revision session, starting 9am although you can join when you want. If we all work on the same question and give ourselves an allocated time per question before sending what we have done. Wait 2 minutes for all answers to come through Then we can see which topics we generally need help on and all focus on them. Just a suggestion. Anyone agree?
    I know we will almost definitely do papers we have done before but practice makes perfect!
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    (Original post by Lilli1997)
    I'm assiming for many of us this is the last exam. It may be good tomorrow to do a group online revision session, starting 9am although you can join when you want. If we all work on the same question and give ourselves an allocated time per question before sending what we have done. Wait 2 minutes for all answers to come through Then we can see which topics we generally need help on and all focus on them. Just a suggestion. Anyone agree?
    I know we will almost definitely do papers we have done before but practice makes perfect!
    Sounds good to me
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    Good luck everybody tomorrow! Let's also after the exam compare our grade boundaries predictions.
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    (Original post by Super199)
    Sounds good to me
    I have an exam this afternoon, but will join in after at about 4pm!
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    So does anybody have anything that they are struggling with?
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    Just to clarify, when asked for the 'contact force' this is the resultant of the normal contact force and friction?
 
 
 

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