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Speed = d/t formula

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    Just wondering why the s=d/t formula can't be used for part 2 of this question ?

    The time in the first part was 4.16

    I got the time, and speed, do distance= 5*4.16 = 20.8 , I know I could use suvat but not sure why this method couldn't be used as I get it wrong.
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    (Original post by Tulian)
    Just wondering why the s=d/t formula can't be used for part 2 of this question ?

    The time in the first part was 4.16

    I got the time, and speed, do distance= 5*4.16 = 20.8 , I know I could use suvat but not sure why this method couldn't be used as I get it wrong.
    s=d/t is for when you have constant speed (or average speed).

    In this situation you have the speed at the start of the motion, but it's changing as the object is decelerating.
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    (Original post by Tulian)
    Just wondering why the s=d/t formula can't be used for part 2 of this question ?

    The time in the first part was 4.16

    I got the time, and speed, do distance= 5*4.16 = 20.8 , I know I could use suvat but not sure why this method couldn't be used as I get it wrong.
    s = d/t can only be used for objects travelling at a constant speed. The block B in this case is decelerating.

    Use s = ut + 0.5 at^2 where:

    s = ?
    u = 5
    a = -1.2
    t = 4.17

    (before anyone points it out, im just too lazy to type in the units above)
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    Thanks alot
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    (Original post by Tulian)
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    Was too late to help out, but I just wanted to wish you luck for your exam.

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Updated: May 4, 2012
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