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Homework Help: Displacement vs time graph for a given equation of acceleration

  1. Sep 30, 2014 #1
    1. The problem statement, all variables and given/known data
    The accompanying graph of position x versus time t represents the motion of a particle. If p and q are both
    positive constants, the expression that best describes the acceleration a of the particle is
    x vs t.png
    2. Relevant equations
    (A) a = – - p – - qt (B) a = - –p + qt (C) a = p + qt (D) a = p – - qt

    3. The attempt at a solution
    option D is mentioned correct in a given solution of the problem. If it is correct then dv/dt = p - qt on itegration will give v = pt -0.5qt^2 +c., for inflexion pts on x-t curve v =0 ,this gives qt^2-2pt-2c=0 , one of the two roots of which becoming negative, which is not realistic with the given graph. I need help to know the real fault made by me.
  2. jcsd
  3. Sep 30, 2014 #2


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    Science Advisor
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    Gold Member

    You mean extremum pts, right?
    You are assuming c is positive? What is the sign of v at t=0?
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