Homework Help: Equation Needed to Figure Resulting Kinetic Energy and Velocities from Fusion

1. May 11, 2009

PHYSICS!!!:-)

Equation Needed to Figure Resulting Kinetic Energy and Velocities from Fusion....

1. The problem statement, all variables and given/known data

Hey,
I am have the initial velocities and masses of nuclei involved in fusion, and am trying to figure out the resulting velocities and kinetic energies. Since this is an inelastic reaction, i cant use Kinetic energy, as it is not conserved. I have the conservation of momentum to use, because it is conserved, but to use it I still need to find velocity. What could i use to find this? Also, if you could clarify how to find the kinetic energies for each resulting particle, it would be greatly appreciated!

2. Relevant equations

Deuterium+Deuterium--> Helium-3 + neutron
each deuteron has K.E. of 69.91 KeV, and a velocity of 2.59 x 10^6 m/s

3. The attempt at a solution
I have already decided that the Law of Conservation of Momentum would be a good equation to use, but i still need an equation to get velocity.

Note: This is not a Homework question, per se. It was simply moved here.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. May 11, 2009

diazona

Re: Equation Needed to Figure Resulting Kinetic Energy and Velocities from Fusion....

Well... the total energy $$E = \sqrt{p^2 c^2 + m^2 c^4}$$ is conserved, you should be able to use that. You'll probably need to look up the rest masses of helium-3 and of the neutron but I don't think they'd be hard to find online.