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Homework Help: Uniform acceleration question

  1. Feb 13, 2012 #1
    1. The problem statement, all variables and given/known data

    a train starts from station a with a uniform acceleration of 5.00 x 10^-1 m/s^2 (east) and attains full speed after 50.0s. It travels at full speed for 1.20 x 10^2 s, then is brought to rest at station b by the application of the brakes which produces a constant acceleration of -2.50 m/s^2 (east). find the distance between station a and station b

    3. The attempt at a solution
    i tried adding station a and b's displacements but it didn't add up to 3.75x10^3 m (the answer)

    i got station a's displacement by finding vfinal then using d=vft-1/2at^2 and added that to the other displacement and yea didn't work.
  2. jcsd
  3. Feb 13, 2012 #2

    Simon Bridge

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    Science Advisor
    Homework Helper

    Draw the v-t graph - the displacement is the area under the graph.
    Note: considering the stations are not moving, both their displacement's are 0.
    Station a will be at position x=0m.

    In the first stage of the journey, you need to find the final speed.
    In the last stage you need to find the time to decelerate to rest.
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