... The speed of the particle relative to the fixed frame will be u = J(uf + us. + uf) (9.79) so that 2 2 -1’2 y=(l - u/c) for a frame of reference moving with the particle. The proper ... If we now consider a group of particles then the four-momentum will be T (0 = Cm,y,(c 11, 4 UJI It is convenient to write this four-vector matrix in a partitioned form such as (0 = ... (4:)’ where (u), is the usual velocity three-vector. Thus there is a scalar part P, = Crn,y,c and a vector part (PI = Cm,y,(u), (9.95) (9.96) (9.97) (9.98) (9.99) (9.100) (9.101)...