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    Use g= 10ms-2

    A firework is buried so that its top is at ground level and its projects sparks all at a speed of 8ms-1. Air resistance may be neglected.

    Calculate the height reached by a spark projected vertically and explain why no spark reach a height greater than this.

    I've tried answering this question but I just get a height of 8m; however this is the wrong answer. Can some please explain which SUVAT equation I need to use and why
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    You know at maximum height it's velocity will be zero. You know it's initial velocity. You know acceleration. That is three of four parts of S^2=So^2+2a(Yf-Yo)
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    (Original post by D-Day)
    You know it's initial velocity.
    I do?
    I didn't think I did.
    I've just tried it with zero and thats not working out either.
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    (Original post by high_maintenance_girl)
    I do?
    I didn't think I did.
    I've just tried it with zero and thats not working out either.
    (Original post by high_maintenance_girl)
    and it projects sparks at a speed of 8ms-1
    You do.
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    (Original post by D-Day)
    You know at maximum height it's velocity will be zero. You know it's initial velocity. You know acceleration. That is three of four parts of S^2=So^2+2a(Yf-Yo)
    that's usually written as v^2 = u^2 + 2as, if it makes it any simpler. you've got a, u and v, you need s.
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    (Original post by imtired)
    that's usually written as v^2 = u^2 + 2as, if it makes it any simpler. you've got a, u and v, you need s.
    Different country, different letters apparently. Forgive my not being British :p:
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    (Original post by D-Day)
    You do.
    I see I see. I just need things spelling out to me lol :p:

    But I still got a problem

    v = 0
    u = 8
    a = - 10

    Using v = u + at, that gives time to reach max height as 0.8 seconds

    Then if i substitute all those values into s = ut + (0.5 x a x t^2)
    I get 3.2 - 3.2 = 0

    The answer is 3.2m though

    I've probably just made a silly mistake; can you see what I'm doing wrong?
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    (Original post by high_maintenance_girl)
    I've probably just made a silly mistake; can you see what I'm doing wrong?
    I was lol
    I found my mistake and I've corrected it.
    Thanks for the help D-day!

    And I was a bit worried about the symbols but I just assumed that was higher level ways of writing the same thing lol.
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    V^2 = U^2 + 2as-----> u = 0

    64/20 = s = 3.2m but you probably figured out that already but i am bored lol
 
 
 
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