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Homework Help: Speed from a skidding stop

  1. Apr 7, 2010 #1
    1. The problem statement, all variables and given/known data

    You are driving your car uphill along a straight road. Suddenly, you see a car run a red light and enter the intersection just ahead of you. You slam on your brakes and skid in a straight line to a stop, leaving skid marks 116 feet long. A policeman observes the whole incident and gives a ticket for exceeding the speed limit of 45 mph. When you get home, you read your physics text book and estimate that the coefficient of kinetic friction between your tires and the road is 0.5, and the coefficient of static friction is 0.80. You go back and measure the angle that the hill makes with the horizontal and find it to be 6 degrees. You look in your owners manual and find that the car weighs 1820 lbs. Find the speed (in MPH) at the instant that you slammed the brakes and determine for yourself if you should fight the traffic ticket in court.

    2. Relevant equations

    3. The attempt at a solution

    I dont remember exactly what i did but i could not get the right answer. it ranged between 22.87 mph to 50.95 mph.
  2. jcsd
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