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Car suspensions problem

  1. Jan 11, 2008 #1
    1. The problem statement, all variables and given/known data
    Ok, I was stumped by this simple online quiz which asked the variation of acceleration with time of a suspension unit of a car after a road bump which follows SHM. (HC0809)

    A. Straight line
    B. Ellipse
    C. Circle
    D. Parabola

    3. The attempt at a solution

    The answer was supposed to be sinusoidal and the quiz gave the answer as A, straight line but that is obviously wrong since

    [tex] a=-w^2x[/tex]

    And the correct form is

    [tex] a=-w^2x_0sinwt[/tex]

    Am i missing something, is the quiz wrong
    Last edited: Jan 11, 2008
  2. jcsd
  3. Jan 11, 2008 #2


    User Avatar

    Was that the exact wording? Maybe there is something you've missed...

    Real suspensions also have damping and under particular conditions the oscillation is barely observable... but I don't think a "straight line" would ever be correct for the acceleration.
  4. Jan 11, 2008 #3
    nooooooo....... the acceleration-displacement graph is a negative gradient straight line, through origin. and the equation is a = -w^2X0

    at least this is what we learn in high school.....
  5. Jan 11, 2008 #4
    If you graph acceleration vs. displacement it is indeed a straight line

    with a slope of -w^2, as given by his equation a=-w^2*x

    However that's not what he was asked for, unless he read the question wrong. Maybe the question made that slip up
  6. Jan 11, 2008 #5
    yes there was damping mentioned in the question but I dont see how a straight line could every beformed if the graph was an acceleration time one
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