You testify as an expert witness in a case involving an accident in which car a slid into the rear of car b, which was stopped at a red light along a road headed down a hill (fig. 6-25). you find that the slope of the hill is u " 12.03, that the cars were separated by distance d " 24.0 m when the driver of car a put the car into a slide (it lacked any automatic anti-brake-lock system), and that the speed of car a at the onset of braking was v0 " 18.0 m/s. with what speed did car a hit car b if the coefficient of kinetic friction was (a) 0.60 (dry road surface) and (b) 0.10 (road surface covered with wet leaves)