Two \(5000-\mathrm{kg}\) freight cars roll toward one another (on at \(1 \mathrm{~m} / \mathrm{s}\) and the other at \(2 \mathrm{~m} / \mathrm{s}\) ) on a level track. Thus before they collide one car's kinetic energy is \(2590 \mathrm{~J}\) arid the other's is \(10,000 \mathrm{~J}\). They collide and couple together. The amount of kinetic energy turned into het (mostly warming the couplers) in the collision is ____________
A. \(1250 \mathrm{~J}\) B. \(2500 \mathrm{~J}\) C. \(7500 \mathrm{~J}\) D. \(11.250 \mathrm{~J}\)
