A free neutron (mass ) is highly unstable, meaning that it won't exist for very long before it decays. When it decays, it decays into a proton (mass , an electron (mass , and an antineutrino.
- If a neutron at rest decays, what will be the total kinetic energy of the proton, electron, and antineutrino when they are very far apart? An antineutrino has no rest energy (or actually it has negligible rest energy).
- Why is it impossible for all three particles to travel in the same direction after the decay?