1.A level test track has a coefficient of road adhesion of 0.80, and a car being tested has a coefficient of rolling friction that is approximated as 0.018 for all speeds. the vehicle is tested unloaded and achieves the theoretical minimum stop in 180 ft. the initial speed was 60 mi/h. ignoring aerodynamic resistance, what is the unloaded braking efficiency?
2.An engineering student is driving on a level roadway and sees a construction sign 500 ft ahead in the middle of the roadway. the student strikes the sign at a speed of 25 mi/h. if the student was traveling at 55 mi/h when the sign was first spotted, what was the students associated perception/ reaction time?