Internal energy

[ougoah]

For a system of particles, how would you prove that the total kinetic energy of the particles is equal to the kinetic energy associated with the center of mass motion plus the "internal energy"? (Where, I think, internal energy is the energy of the particles seen from the center of mass reference frame.)

Thanks

 

[ougoah]

I don't know why this was moved, since it is not a homework question; my textbook is missing this proof.