1. The problem statement, all variables and given/known data Two railroad cars, each of mass 7650 kg and traveling 95 km/h in opposite directions, collide head-on and come to rest. How much thermal energy is produced in this collision? 2. Relevant equations I'm assuming: KE=1/2mv^2 HE=mc(delta)T 3. The attempt at a solution The answer is 5.3x10^6 Joules, or 5300000 Joules. I don't see enough information in the question to find thermal energy, yet somehow an answer was reached. I'm guessing that there is some mix of equations or there is another way of solving that I'm not aware of... A variation of the question is on my homework, so any help in figuring out how this was done is greatly appreciated. Thank you!