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Homework Help: Minimum distance to avoid a collision

  1. Sep 20, 2009 #1
    1. The problem statement, all variables and given/known data
    While learning to drive, you are in a 1500 kg car moving at 19.0 m/s across a large, vacant, level parking lot. Suddenly you realize you are heading straight toward a brick sidewall of a large supermarket and are in danger of running into it. The pavement can exert a maximum horizontal force of 6000 N on the car.

    3. The attempt at a solution
    Suppose you apply the brakes and do not turn the steering wheel. Find the minimum distance you must be from the wall to avoid a collision

    could somebody give me some hints on this? i can't figure out any method to find the minimum distance the car will stop before hit the wall.
    since the question never say it is under a constant acceleration or increasing deceleration, how do i know what formula should i use?
    i try to use F=ma, but it seems like lack of some information.
  2. jcsd
  3. Sep 20, 2009 #2
    You know your initial velocity and your final velocity. You can find out your acceleration since you know your mass. Now you just need to find the distance that acceleration would have to be applied in order to change between your initial and final velocities.
  4. Sep 20, 2009 #3
    but how do i know the acceleration is constant or not?

    and why i could assume the force before collision is 6000N since it is the force exerted for collision?
  5. Sep 20, 2009 #4
    The question mentions that the pavement is providing the force, so I'm assuming it means the force of friction on the car after brakes are applied.

    For the acceleration, you know that the car's mass is a constant, as well as the force on the car. If F=ma, then the acceleration must also be constant.
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