1. The problem statement, all variables and given/known data A car driving at a speed of 60km/h at a horizontal road. The car accelerates to 65km/h, and then the engine gets deactivated. The speed then decreases to 55km/h in a time of 7,2 seconds. The mass of the car is 1450 kg(the car, passenger etc...) 2. Relevant equations What is the driving force of a car that's driving at the speed of 60km/h? 3. The attempt at a solution Until here I'm not understanding so much, I thought maybe to subtract the sum of the forces by the mass, but I do not can't find a reasoning for that.