A car travelling with a constant speed of 80 km/h passes a stationary motorcyle policeman. The policeman sets off in pursuit, accelerating to 80 km/h in 10.0 s and reaching a constant speed of 100km/h after a further 5.0 s. At what time will the policeman catch up with the car? I am stuck in the above problem. I do not know what to do. Any help/complete working out solution in the above problem will be appreciated! Please provide hints for me to work this out.