A railroad car, with a mass of 25,000 kg, is moving north along a track at 4.5 m/s. It has a collision with another railroad car that is full of coal and therefore has a much larger mass of 58,000 kg. The two railroad cars "couple" and move as one unit after the collision. What is the final velocity of the two railroad cars? Assume the second car was initially at rest. (Round your answer to the nearest tenth.)