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Help Please: M1 Kinematics Question to do with an increasing function and distance. watch

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    I'm honestly stuck on this question, and how it's solved. I'll give you the question and the solution below.
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    (Original post by BrainJuice)
    I'm honestly stuck on this question, and how it's solved. I'll give you the question and the solution below.
    What is it that you dont understand?
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    (Original post by BrainJuice)
    I'm honestly stuck on this question, and how it's solved. I'll give you the question and the solution below.
    The particle moves at t=0 with a velocity v=20. In the first twelve seconds, it's velocity decreases from v=20 to v=0 (which means it's stationary) then continues to decrease (moving backwards). Your answer in part (a) calculates the displacement of the particle, i.e the distance between O and A. Which is different from the distance of the particle, which is the distance the particle covered from v=20 to v=0, plus the distance covered as it moved backwards. In part (a), when the particle moves backwards, it sort of 'erases' the distance covered, hence the displacement being only 60 metres.

    So to calculate the distance covered from v=20 to v=0, you do what the solution did to get s=80. Then you know that the distance traveled from v=0 to v=whatever it is when t=12 is given by 80-60 = 20. (since OA = 60),

    Then you know that the total distance covered is 80 + 20 = 100.

    Does that make sense?
 
 
 
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