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http://answers.yahoo.com/question/index?qid=200908...

Two seconds. This is an easy problem to solve if you draw it out on a time line to see where the vehicles are with the passage of each second. In the 0.700 second of reaction time, the police car covered 10.5 meters and the speeder covered 30.1 meters, and the distance beween the police car and the speeder increased by 19.6 meters (43 m/s minus 15 m/s multiplied by 0.7) One second later, the poice car covered 19.6 meters (15 m/s plus 4.6 m/s) and the speeder covered 30.1 meters (the constant), and the distance between the cars reduced to 10.5 meters (30.1 minus 19.6) One second after that, the police car covered 40.76 meters (4.6 m/s squared plus 19.6 m/s0, the speeder covered another 30.1 meters, and the distance between the cars reduced to almost zero. 10.5 meters minus the closure rate of 40.76 m/s minus 310.1 m/s). Hope they didn't collide, and I hope the speeder has a lot of money for the speeding ticket and increased insurance premiums he'll pay for the next three years... Best Regards, Grandpa Frank Indianapolis