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Homework Help: What equation could I use for this?

  1. Sep 27, 2011 #1
    1. The problem statement, all variables and given/known data

    Two particles are at the same point at the same time, moving in the same direction. Particle A has an initial velocity of 6.9 m/s and an acceleration of 1.8 m/s2. Particle B has an
    initial velocity of 2.4 m/s and an acceleration of 5.7 m/s2.

    At what time will B pass A?

    2. Relevant equations

    [itex]\Delta[/itex]x = vit + 1/2at2

    3. The attempt at a solution

    I'm just wondering what equation I should use for this. I think I need to set up a system, but I don't see why I would need displacement for this. The only information the question gives us is vi for both, the acceleration for both, and the fact that they're going the same direction.

    I really don't understand how I would go about solving it. Knowing the equation(s) to use would be a great start!

    I'm really discouraged. I just tried setting two equations equal and I got the wrong answer... I don't know what to do.

    Thank you so much!

    EDIT: I calculated with the quadratic equation wrong somehow, but found the answer.
    Last edited: Sep 27, 2011
  2. jcsd
  3. Sep 27, 2011 #2


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    Staff Emeritus
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    One more piece of information.

    When B passes A, they're at the same location.
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