Answer:
72.3 MeV
Explanation:
E = Total energy of muon = 178 MeV
[tex]E_0[/tex] = Rest energy of a muon = 105.7 MeV
Kinetic energy of the muon at the surface of the Earth is given by the difference of the total energy and the rest energy of the muon
[tex]K=E-E_0\\\Rightarrow K=178-105.7\\\Rightarrow K=72.3\ MeV[/tex]
The kinetic energy of a muon at the surface is 72.3 MeV