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Homework Help: Car's maximum velocity in a straight then deceleration!

  1. Feb 16, 2009 #1
    We are doing a project to find the quickest time round a given track in a car.
    friction: k=1.6
    mass of car m=750kg
    power of engine w=350kw
    distance x=500m

    After a corner, the car comes out at velocity=31.9m/s
    There is a 500m straight next but have to finish it at 31.9m/s for next corner.
    I need to know the fastest way to complete the 500m.
    how can i work out the maximum velocity i can go and when to start braking?
    i think we found the braking eqaution was a=-gk but we are basically really stuck!
    any help would be greatly appreciated!
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 16, 2009 #2


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    Welcome to PF!

    Hi leathley! Welcome to PF! :smile:

    Call the maximum speed v …

    then use the appropriate constant acceleration equation twice, once to find the distance needed to accelerate up to that speed, and once to find the distance needed to decelerate under braking back to 31.9m/s …

    then choose v so that the distances add up to 500m :wink:
  4. Feb 16, 2009 #3
    distance needed to get to vmax, s = (vmax^2 -vi^2)/2a or what???

    can't just do the reverse for the other distance because s1 + s2 will cancel each other out.
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