Charged pion decay We consider the decay of a charged 7-meson, or pion, which is initially at rest in the labo- ratory frame. Most charged pions decay according to the scheme +p+ +V/ (2) In this expression, ut represents a muon, a particle similar to the electron (or positron), but with a rest mass energy m,c= 105.7 MeV. The symbol, is for a neutrino (of muon-kind), a particle of zero rest mass, and therefore, like a photon, it must travel at the speed of light. When the above process occurs, the charged muons can be detected, and are found to have a kinetic energy of 4.1 MeV. Based on just the information given here, what is the mass of the ? Express your answer as a rest mass energy, m+c, in MeV. Hint: Use the conservation of both total momentum and total energy.