Question

russell was driving on a gravel road that had a 20 mph speed limit posted. a car ahead of him pulled out from a parking lot causing russell to immediately apply the brakes. his tires left two skid marks of lengths 60 feet and 62 feet. the road had a drag factor of 0.47. his brakes were operating at 95% efficiency. the police gave russell a ticket for speeding. russell insisted that he was driving under the limit. who is correct (the police or russell)?explain.

Answer 1

Calculations based on skid mark length and drag factor indicate that Russell was traveling at approximately 34.26 mph, exceeding the 20 mph limit. Therefore, the police were correct to issue a speeding ticket.

Step-by-step explanation:

Russell was driving on a gravel road with a drag factor of 0.47, and his tires left skid marks of lengths 60 feet and 62 feet when he applied his brakes. The question asks whether Russell was speeding or not, based on the evidence of the skid marks and the efficiency of his brakes.

We can determine if Russell was speeding by using the formula for calculating the speed of a car based on the length of skid marks and the coefficient of friction. The basic formula for speed based on skid marks is Speed = sqrt(2 × drag factor × efficiency × length of skid marks × 32.2).

Using the information given, Russell's estimated speed can be calculated as follows:

• Speed = sqrt(2 × 0.47 × 0.95 × (average skid mark length in feet) × 32.2)
• Speed = sqrt(2 × 0.47 × 0.95 × 61 × 32.2)
• Speed = sqrt(2 × 0.47 × 0.95 × 61 × 32.2) ≈ 34.26 mph

At approximately 34.26 mph, Russell was indeed exceeding the posted 20 mph speed limit. Therefore, the police were correct in issuing the speeding ticket.