paradox with Newton's E=1/2mv2 ??? Looking for clarification... I don't understand why these points of view don't balance. This is non-relativistic. If two objects are travelling towards each other from opposite walls of a room, then the sum of their Kinetic energies relative to the room does not seem to match the kinetic energy relative to each other. For example. relative to the room, if each has a mass of 1Kg and is travelling at 10m/s, then since E=1/2mv2, each will have a Kinetic energy of 50J, for a total of 100J. But relative to each other, they are travelling at each other at 20m/s. Relative either one of the objects, the other then has a Kinetic energy of 200J. Also note, each object could have acclerated from each wall according to this formula in such a way that it is expected that they each have 50J of energy. But according to the formula, if the two collide (and stop), they ought to release 200J of energy into another form. ??? Thanks.