In an auto accident, a car hit a pedestrian and the driver thenlamed on the brak
ID: 1741869 • Letter: I
Question
In an auto accident, a car hit a pedestrian and the driver thenlamed on the brakes to stop the car. During the subsequent trial,the driver’s lawyer claimed that he was obeying the posted 35mph speed limit, but that the legal speed was too high to allow himto see and react to the pedestrian in time. You have been called inas the state’s expert witness (since you have taken Physics218, you must be an expert….). Your investigation of theaccident yields the following measurements: The skid marks madewhile the brakes were applied were 277 ft long, and the tread onthe tires produced a coefficient of kinetic friction of 0.64 withthe road. What was the speed of the driver of the when he struckthe victim?
Give your answer in miles per hour (since the courts don’tuse SI units) to the nearest whole number
In an auto accident, a car hit a pedestrian and the driver thenlamed on the brakes to stop the car. During the subsequent trial,the driver’s lawyer claimed that he was obeying the posted 35mph speed limit, but that the legal speed was too high to allow himto see and react to the pedestrian in time. You have been called inas the state’s expert witness (since you have taken Physics218, you must be an expert….). Your investigation of theaccident yields the following measurements: The skid marks madewhile the brakes were applied were 277 ft long, and the tread onthe tires produced a coefficient of kinetic friction of 0.64 withthe road. What was the speed of the driver of the when he struckthe victim?
Give your answer in miles per hour (since the courts don’tuse SI units) to the nearest whole number
Explanation / Answer
Based on information given we can't say what was the speed ofthe car when it hit the driver, but we can say what was theminimun speed the car was traveling before the brakes wereapplied Let's say the car hit the pedestrian with very little energy,then Ke= Wf Ke= 0.5mV2 Wf = fS f= mg we have 0.5mV2 = mg S V= (2g S) V= ( 2 x 0.64 x 32 x 277) V= 106 ft/s = 106 x 3600 / 5280 V= 72 mph Verdict - Gulty! Verdict - Gulty!Related Questions
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