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What was the car's velocity at t=0?

  1. Sep 20, 2009 #1
    1. The problem statement, all variables and given/known data
    A car accelerates at 1.75 m/s2 along a straight road. It passes two marks that are 30.3 m apart at times t=3.80 s and t=5.15 s. What was the car's velocity at t=0?


    2. Relevant equations



    3. The attempt at a solution
    Im actually not quite sure how to approach this question. Is there some way that i can find the velocity at the beginning of the time interval that is given?
     
  2. jcsd
  3. Sep 20, 2009 #2
    Re: Velocity

    What is the average speed over the interval from 3.8s to 5.15 s?

    exactly when does the car have this average speed?
     
  4. Sep 20, 2009 #3
    Re: Velocity

    the average velocity over that time interval is 22.4 m/s. but im not sure what you mean by:
     
  5. Sep 21, 2009 #4
    Re: Velocity

    if the car goes has speed [itex] v_i [/itex] at the start of the interval and [itex] v_f [/itex] at
    the end of the interval, its average speed is [itex] (v_i + v_f)/2 [/itex]. The speed at _______
    is also [itex] (v_i + v_f)/2 [/itex]. (with constant acceleration)
     
  6. Sep 21, 2009 #5
    Re: Velocity

    so the middle of the interval (4.48s) would also have the velocity of 22.4 m/s ??
     
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