A railroad tank car rolls on a track at 3.45 m/s toward two identical coupled tank cars, which are rolling in the same direction as the first, but at a speed of 1.20 m/s. The first reaches the second two and all couple together. The mass of each is 3.45 x 104 kg. (a) What is the speed (in m/s) of the three coupled cars after the first couples with the other two? (Round your answer to at least two decimal places.) m/s (b) Find the (absolute value of the) amount of kinetic energy (in J) converted to other forms during the collision.