When a driver decides to stop a car, it takes time first for the driver to react and put a foot on the brake, and then it takes additional time for the car to slow down. The total distance traveled during this period of time is called the stopping distance of the car. For some cars, the stopping distance d, in feet, is given by the equation  d = 0.05r2 + 0.5r,  where r is the speed of the car in miles per hour. (a) Find the distance needed to stop a car traveling at 60 miles per hour.  ft (b) If skid marks at an accident site are 30 feet long, how fast was the car traveling? (Round your answer to the nearest integer.)  mph

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Author:James Stewart, Lothar Redlin, Saleem Watson
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When a driver decides to stop a car, it takes time first for the driver to react and put a foot on the brake, and then it takes additional time for the car to slow down. The total distance traveled during this period of time is called the stopping distance of the car. For some cars, the stopping distance d, in feet, is given by the equation 

d = 0.05r2 + 0.5r,

 where r is the speed of the car in miles per hour.

(a) Find the distance needed to stop a car traveling at 60 miles per hour.
 ft

(b) If skid marks at an accident site are 30 feet long, how fast was the car traveling? (Round your answer to the nearest integer.)
 mph
Expert Solution
Step 1

Given equation,

d=0.05r2+0.5r                                      ....(1)

Where r is a speed and d is a distance.

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