1. The problem statement, all variables and given/known data A nuclear fusion reaction occurs when a deuterium nucleus, mass 2m, and a tritium nucleus, mass 3m, combine (each with velocity v in opposite directions). Most of the energy released in the fusion is carried away in the kinetic energy of the product neutron, mass m, and velocity 5v. The other product is a helium nucleus, mass 4m, and velocity v. (a) Show in terms of m and v that momentum is conserved in the process. I've done this part, I don't need help with it. I'm just posting it incase it's a sub-step for the next part. The answer is -mv=-mv (b) Calculate the kinetic energy released in the fusion in terms of m and v. I'm stuck with part b. For part a I had to use all the data in the question, I'm guessing that for part b I only have to use the masses and velocities before the collision. 2. Relevant equations Ek = 0.5mv2 3. The attempt at a solution This is what I've done so far: Ek = 0.5mv2 v1 = 1v m1 = 2m v2 = 1v m2 = 3m Ek1 = 0.5m1v12 Ek1 = 0.5x2m1v2 Ek1 = mv2 Ek2 = 0.5m2v22 Ek1 = 0.5x3m1v2 Ek1 = 1.5mv2 EkT = Ek1+Ek2 EkT = (mv2)+(1.5mv2) But the answer in the book is EkT = 12mv2... I think I may have messed up in the algebra, or maybe I need to use the data after the collision too.