Ok this'll probably change my perception on what relativistic kinetic energy is so here goes. Lets say you have a lab experiment ready to fire a particle at .6c into a wall or something (or maybe even another group of particles). Lets say you fire the entire lab experiment off from an observer at .35c. Now, using relativistic kinetic energy, the particle according to people traveling with the lab experiment will hit the other particles with a certain KE right? Now, what would the KE be relative to the observer whos standing still? It seems like it would be a different KE and deliver more energy to the particles according ot the observer. I think i might have realized why thats not the case (as i was writing the question!), but i just wanted to ask to make sure i know why im wrong.