You have a system consisting of two point masses m

_{1}and m

_{2}. m

_{1}is moving towards m

_{2}with constant speed v (with m

_{2}stationary). Now, if I'm not mistaken, you can equivalently say that m

_{2}is moving towards m

_{1}with speed v. My question is, what expression correctly describes the total kinetic energy of the system: 1/2m

_{1}v

^{2}or 1/2m

_{2}v

^{2}? Or can they both be considered correct in some way? Maybe I'm just messing up my relative velocities.

Just a note: this is not a homework problem, just something I started wondering about.