Reading assignment: 39.7-39.9
What is the maximum momentum that a particle with mass m can
There is no maximum! Momentum is gamma*m*v, and gamma approaches infinity as the velocity approaches the speed of light.
I often call "E=mc2" the most misquoted equation in history. Why
might that be?
Because E does *not* equal mc^2. E = *gamma* times mc^2. See Eqn 39.26 (8th edition). The quantity mc^2 is only the rest energy.