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    A train is uniformly retarded from 35 m/s to 21 m/s over a distance of 350m. Calculate
    A) The retardation
    b) The total time taken under this retardation to come to rest from a speed of 35m/s

    (Letts A level mathematics)

    i got first part

    v = 21
    u = 35
    s = 350
    a = ?

    21² = 35² + 700a
    a = 441-1225/700

    = -1.12 ms-2

    The second part i cannot seem to get, i'm using the formula

    s = ut + 0.5at²

    350 = 35t + (0.5)(1.12)(t²)

    350 = 35t + 0.56t²

    0 = 0.56t²+35t-350

    bang that in the quadratic formula and you get...
    some wierd answers
    can anyone help?
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    (Original post by thewebmaster)
    A train is uniformly retarded from 35 m/s to 21 m/s over a distance of 350m. Calculate
    A) The retardation
    b) The total time taken under this retardation to come to rest from a speed of 35m/s

    (Letts A level mathematics)

    i got first part

    v = 21
    u = 35
    s = 350
    a = ?

    21² = 35² + 700a
    a = 441-1225/700

    = -1.12 ms-2

    The second part i cannot seem to get, i'm using the formula

    s = ut + 0.5at²

    350 = 35t + (0.5)(1.12)(t²)

    350 = 35t + 0.56t²

    0 = 0.56t²+35t-350

    bang that in the quadratic formula and you get...
    some wierd answers
    can anyone help?
    S= 350 doesn't apply to this part.

    Use v=u+at with u=35, v=0, and your value for a.

    Aitch
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    (Original post by thewebmaster)
    A train is uniformly retarded.....
    I don't do Mechanics so I can't answer your question but :rofl: at that part
 
 
 
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Updated: July 2, 2005

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