Imagine an aspiring young lab coordinator at age 17 getting a rusty ’66 pickup r
ID: 1333414 • Letter: I
Question
Imagine an aspiring young lab coordinator at age 17 getting a rusty ’66 pickup ready for a Styx concert when another teenager comes speeding around a corner who dings his sweet ride halfway down the block. The offending vehicle locked its brakes and left an 88 ft long skid mark (as measured by police) on the dry asphalt.
As the responding officer on the scene, use the following information (cops actually have these) to determine whether or not to add a ticket for speeding in a 30 mph zone in addition to reckless driving. Cite evidence.
Coefficient of Friction between commercial tires and various road surfaces and conditions Concrete Asphalt Dr 0.68 0.67 Wet 0.58 0.53Explanation / Answer
Friction coefficient for Dry Asphalt = 0.67
decelaration will = u.g = 0.67 x 9.81 =6.57 m/s^2
Using v^2 - u^2 = 2ad
d = 88 ft = 88 x0.3048 =26.82 m
0 - u^2 = 2 x -6.57 x 26.82
u = 18.77 m/s = 18.77 x 1/1609 m / 1/3600 h = 42 mph
Yes , add a ticket.