Quadratic Equaion Question Alfonso drives a red Nissan Micra. The total stopping distance (tsd) for the car, measured in metres, is given by the formula:

tsd = reaction time (rt) + braking distance (bd)

Alfonso's reaction time is given by the formula rt = ¼ v and the car's braking distance is given bd = ⅛ v² where v is his speed measured in metres per second. whilst driving around town, Alfonso is forced to perform an emergency stop; his total stopping distance is 15 metres. calculate the speed Alfonso was travelling, give your answer in km/h.