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Coefficient of friction and drunk driver

  1. Oct 29, 2008 #1
    1. The problem statement, all variables and given/known data

    A drunk driver in a 2400kg car plows into a 1200kg parked car with its brake set. Police measurements show that the two cars skid together a distance of 25m before stopping.

    If the effective coefficient of friction is 0.70, how fast was the drunk going just before the collision?

    2. Relevant equations

    Mv^2 / 2 = (M+m)μg * S i used this equation


    and i got 7.246 for v

    what did i do wrong?

  2. jcsd
  3. Oct 29, 2008 #2
    It looks to me like when you subbed in your values for the equation, you forgot acceleration due to gravity.
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