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Homework Help: Car Velocity Question

  1. May 14, 2009 #1
    1. The problem statement, all variables and given/known data
    Part 1 Consider a car which is traveling along a straight road with constant acceleration a. There are two checkpoints, A and B , which are a distance 81.4 m apart. The time it takes for the car to travel from A to B is 5.89 s.

    Part 2 Find the velocity VB for the case where the acceleration is 7.45 m/s^2.

    3. The attempt at a solution
    acceleration multiplied by the final time does not give me the answer
    Last edited: May 14, 2009
  2. jcsd
  3. May 14, 2009 #2


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    Gold Member

    What is VB? Is that supposed to be the velocity once it reaches checkpoint B?
  4. May 14, 2009 #3
    yea my browser won't load the functions so it should read V(sub)B which is the velocity once it reaches checkpoint B.
  5. May 14, 2009 #4


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    Gold Member

    Perhaps start by finding what the velocity at checkpoint A is.
  6. May 14, 2009 #5
    how would you go by doing that?
  7. May 14, 2009 #6
    anyone? I have no clue how to find the velocity at either checkpoints with the given data
  8. May 14, 2009 #7


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    Homework Helper

    Take A to be the initial point, time = 0.
    Then for the trip to B you know d, t, and a. Don't know Vi.
    You could make progress with d = Vi*t + 0.5a*t^2 which has only one unknown.
    There is another formula like that with a Vf instead of a Vi which would get you to the answer in one step.
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