(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Unstable, subatomic particles called muons have a rest energy of 105.7 MeV and a speed of 0.994c. If a muon were to decay and produce an electron and a photon, what would be the momentum of the electron as measured by an observer in the muon's frame? HINT: assume that the electro goes in the +x direction, the photon goes in the -x direction, and the muon is at rest in its own frame.

2. Relevant equations

E = mc^2 + K; p = gamma*m*v; numerous other forms of relativistic energy equations

3. The attempt at a solution

By the hint, (muon is at rest) we can assume that the initial momentum is zero. By conservation of momentum, initial momentum = final momentum thus, momentum of the electron = momentum of the photon.

This is as far as I can get. The posted answer is 52.8 MeV/c.

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# Homework Help: Relativistic momentum - muon decay

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