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Homework Help: Initial Velocity and Acceleration-

  1. Sep 10, 2010 #1
    Initial Velocity and Acceleration--Please Help!

    1. The problem statement, all variables and given/known data

    You are driving along a straight section of roadway (x-axis). You spot a police officer and apply the brakes, slowing down at a constant rate. Your positions (in meters) at successive time intervals of 0.515 s are tabulated below as function of time. (1) Calculate the initial speed (i.e., the speed at t=0, the time at which the brakes are first applied.). (2) Calculate your acceleration along the x-axis, ax.
    NOTE: Both answers must be correct to get credit.
    x (m) 6.00 18.46 30.00 40.60
    t (s) 0.000 0.515 1.030 1.545

    2. Relevant equations


    3. The attempt at a solution

    First, i found the velocity by doing the slopes, and the points i got were

    .2575, 24.194
    .7725, 22.408
    1.2875, 20.583

    i then found the slopes of those to get the acceleration, and i got -3.468 and -3.544. therefore the average acceleration is -3.5 m/s2

    i then plugged the acceleration into the equation above and got that the initial velocity would be 25.1 m/s

    i'm not sure about this answer, and any help would be greatly appreciated!!
  2. jcsd
  3. Sep 10, 2010 #2
    Re: Initial Velocity and Acceleration--Please Help!

    Please help! This is due really soon!
  4. Sep 10, 2010 #3


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    Homework Helper

    Re: Initial Velocity and Acceleration--Please Help!

    Your solution is OK, but I got 25.4 m/s for the initial velocity, using the first interval.

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