1. The problem statement, all variables and given/known data You have been called to testify as an expert witness in a trial involving an automobile accident. The posted speed limit was 70 km/h . The driver of the car slammed on his brakes, locking the wheels, and left skid marks as the car skidded to a halt. You measure the length of these skid marks to be 61.9 m, and determine that the coefficient of kinetic friction between the wheels and the pavement at the time of the accident was 0.460. What was the speed of the car? 2. Relevant equations fk = uk X n 3. The attempt at a solution I have no clue on how to approach this problem. No velocity is given(speed limit is irrelavent i think) and only the displacement and the kinetic friction coefficient is given. And especially without the mass, i am clueless. Any help would be appreciated. Thanks.