A police car is stationary by the roadside in a zone with a posted 50 km/hr speed limit, when it is passed by a motorist with speed, 73 km/hr. The instant the speeder passes, the police car accelerates at 3.6 m/s^2 to chase the speeder. Assuming the speeding motorist holds the same speed during the chase, how long does the police car ake to catch up to the motorist?