A light train made up of two cars is traveling at 90 km/h when the brakes are applied to both cars. Knowing that car A has a mass of 25 mg and car B a mass of 20 mg, and the braking force is 30 kn on each car, determine (a) the distance traveledby the train before it comes to a stop (b) the coupling force between the cars as the is slowing down.