e t a S t 1 d ? f a V f 1 2.20 A driver is traveling at 90 mi/h down a 3% grade on good, wet pavement. An accident investigation team noted that braking skid marks started 410 ft before a parked car was hit at an estimated 45 mi/h. Ignoring air resistance, and using theoretical stopping distance, what was the braking efficiency of the car? 2.21 A small truck is to be driven down a 4% grade at 70 mi/h. The coefficient of road adhesion is 0.95, and it is known that the braking efficiency is 80% when the truck is empty and decreases by one percentage point for every 100 lb of cargo added. Ignoring aerodynamic resistance, if the driver wants the truck to be able to achieve a minimum theoretical stopping distance of 275 ft from the point of brake application, what is the maximum amount of cargo (in pounds) that can be carried?

Traffic and Highway Engineering
5th Edition
ISBN:9781305156241
Author:Garber, Nicholas J.
Publisher:Garber, Nicholas J.
Chapter7: Intersection Design
Section: Chapter Questions
Problem 11P
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Question
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2.20 A driver is traveling at 90 mi/h down a 3%
grade on good, wet pavement. An accident
investigation team noted that braking skid marks
started 410 ft before a parked car was hit at an
estimated 45 mi/h. Ignoring air resistance, and using
theoretical stopping distance, what was the braking
efficiency of the car?
2.21 A small truck is to be driven down a 4% grade
at 70 mi/h. The coefficient of road adhesion is 0.95,
and it is known that the braking efficiency is 80%
when the truck is empty and decreases by one
percentage point for every 100 lb of cargo added.
Ignoring aerodynamic resistance, if the driver wants
the truck to be able to achieve a minimum
theoretical stopping distance of 275 ft from the
point of brake application, what is the maximum
amount of cargo (in pounds) that can be carried?
Transcribed Image Text:e t a S t 1 d ? f a V f 1 2.20 A driver is traveling at 90 mi/h down a 3% grade on good, wet pavement. An accident investigation team noted that braking skid marks started 410 ft before a parked car was hit at an estimated 45 mi/h. Ignoring air resistance, and using theoretical stopping distance, what was the braking efficiency of the car? 2.21 A small truck is to be driven down a 4% grade at 70 mi/h. The coefficient of road adhesion is 0.95, and it is known that the braking efficiency is 80% when the truck is empty and decreases by one percentage point for every 100 lb of cargo added. Ignoring aerodynamic resistance, if the driver wants the truck to be able to achieve a minimum theoretical stopping distance of 275 ft from the point of brake application, what is the maximum amount of cargo (in pounds) that can be carried?
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