Colision Investigation Problem

1. The problem statement, all variables and given/known data

You are starting a job for Montreal Police Colision Investigators. Your boss tells you to file a report on an accident on Notre-Dame Street. There has been an accident involving 2 cars.

Your findings are as follows:

  • Numerous debris were found at a distance of 12.25 m from the car
  • The two cars stuck together and there are skid marks over 12.25 m
  • There are also skid marks over a distance of 30 m before your debries
  • The posted speed limit is 70 km/h
  • Other data: m1=2,674 kg and m2=1,100kg
  • From a friction block: Fv= 88.2N and Fh = 75.8N
  • The second car was at rest

Write a report for your superior on wether the car at fault should be charged with speeding (over 70 km/h)

2. Relevant equations

μk = Fk/Fn

3. The attempt at a solution

The coeficent of kinetic friction is 0.86 (μk = Fv/Fh)
We have:
Mass of both cars
initial velocity of second car (0)
final velocity of first car (0)
distance of skid marks

We need 2 know:

Initial velocity of 1st car.

How can we do this with only mass, distance of skid marks, and coeffiecent of friction?

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