Say the red and blue ball are side by side and the yellow ball is fifty radius's away. If you are on the yellow ball the other two seem to be moving at 100m/s toward you. This seems as though you have two 1kg balls moving at 100m/s and on the frame of the two balls the yellow ball is seeming to move toward you 1 1kg ball moving at 100m/s. Which is the answer. The answer is 1kg ball moving at 100m/s. This is because the two ball have greater mass and gravity, so there time dilation is greater and there inertia is greater, so they would be still or the center of the universe. If a planet of earth size is in the path of Jupiter. and the collision was going to happen at 10,000 mph, which force is the impact going to have. The answer is the sum is the biggest so it set the dimensions of reality. Some the sun would be center and which one is moving and the energy applied is figured by the relation ship of the sun and if the planets are a lone it would be figured by Jupiter be cause it is center. Thing on earth are figured by movement compared to earth. If the three balls are triangle in their placement then the out come would go by the system of all three and if only two balls hit it would make little difference because the energy would be the same.