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Answer: Legal Physics. In an auto accident, a car hit a
Chapter 7, Problem 57P(choose chapter or problem)
Problem 57P
Legal Physics. In an auto accident, a car hit a pedestrian and the driver then slammed on the brakes to stop the car. During the subsequent trial, the driver’s lawyer claimed that he was obeying the posted 35-mph speed limit, but that the legal speed was too high to allow him to see and react to the pedestrian in time. You have been called in as the state’s expert witness. Your investigation of the accident found that the skid marks made while the brakes were applied were 280 ft long, and the tread on the tires produced a coefficient of kinetic friction of 0.30 with the road. (a) In your testintony in court, will you say that the driver was obeying the posted speed? You must be able to back up your conclusion with clear reasoning because one of the lawyers will surely cross-examine you. (b) If the driver’s speeding ticket were $10 for each mile per hour he was driving above the posted speed limit, would he have to pay a fine? If so, how much would it be?
Questions & Answers
QUESTION:
Problem 57P
Legal Physics. In an auto accident, a car hit a pedestrian and the driver then slammed on the brakes to stop the car. During the subsequent trial, the driver’s lawyer claimed that he was obeying the posted 35-mph speed limit, but that the legal speed was too high to allow him to see and react to the pedestrian in time. You have been called in as the state’s expert witness. Your investigation of the accident found that the skid marks made while the brakes were applied were 280 ft long, and the tread on the tires produced a coefficient of kinetic friction of 0.30 with the road. (a) In your testintony in court, will you say that the driver was obeying the posted speed? You must be able to back up your conclusion with clear reasoning because one of the lawyers will surely cross-examine you. (b) If the driver’s speeding ticket were $10 for each mile per hour he was driving above the posted speed limit, would he have to pay a fine? If so, how much would it be?
ANSWER:Solution 57P
Step 1:
Given data:
Coefficient of kinetic friction
Speed limit for car driver is
The skid marks made while the brakes were applied were at a distance