Amuon is traveling at 0.995 c. what is its momentum? (the mass of such a muon at rest in the laboratory is 207 times the electron mass.)

The momentum of a relativistic particle is given by

where
is the relativistic factor
is the rest mass of the particle
v is the speed particle

The rest mass of the muon is 207 times the rest mass of the electron:

The muon is moving at speed 0.995 c, therefore its velocity is

And the relativistic factor is


If we plug these numbers into the first equation, we find the muon momentum: