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    https://3b0a7b1bc87f5381e60f8f717510...%20Edexcel.pdf

    question 4

    i got
    s=2t-4.9t²-50
    and
    s=20-4.9t²

    however when i equated them to find time i got a negative, if this was a real exam i'd obviously disregard the negative and just make the answer positive xD since it's time

    18t=-50
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    (Original post by notnotbob)
    https://3b0a7b1bc87f5381e60f8f717510...%20Edexcel.pdf

    question 4

    i got
    s=2t-4.9t²-50
    and
    s=20-4.9t²

    however when i equated them to find time i got a negative, if this was a real exam i'd obviously disregard the negative and just make the answer positive xD since it's time

    18t=-50
    I believe you went wrong in your first suvat, it should be s=2t-4.9t^{2}+50 as when t=0, the ball is 50m above the ground and not -50m
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    That gets the answer to be t=\frac{50}{18}
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    (Original post by Cryptokyo)
    I believe you went wrong in your first suvat, it should be s=2t-4.9t^{2}+50 as when t=0, the ball is 50m above the ground.
    but i said s+50 not s-50

    for the first particle it is 50 m above ground, thus taking ground height as S the first particle must have height s+50 not s-50 xD
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    The reason it that suvats lie to you. It is formally s=s_{0}+ut+\frac{1}{2}at^{2} where s_{0} is the initial displacement of the particle. In this case s_{0}=50 so it is s=50+2t-4.9t^{2}

    The problem your equation is that when t=0, s=-50

    (Original post by notnotbob)
    but i said s+50 not s-50

    for the first particle it is 50 m above ground, thus taking ground height as S the first particle must have height s+50 not s-50 xD
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    (Original post by Cryptokyo)
    The reason it that suvats lie to you. It is formally s=s_{0}+ut+\frac{1}{2}at^{2} where s_{0} is the initial displacement of the particle. In this case s_{0}=50 so it is s=50+2t-4.9t^{2}

    The problem your equation is that when t=0, s=-50
    ah good point so the 50 should've gone on the other side anyway, thanks
 
 
 
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