Hi there, i've been coding a simulator (ellastic collisions with billard balls) and i wanted to check if the results the program outputs are indeed valid. My doubts are with multiple collisions at the exact same instant and with kinetic energy as well. . Just to make clear, a possible multiple collision with particles A, B and C could be: A hits C, and B hits C, at the exact moment . The results i've ended with, is that the momentum is always preserved... independent of the type of collision (single or multiple collision) But that doesn't happen with KE when it's a multiple collision. . example (particles A to D move towards X at the same velocity and are at the same distance): .......A . B.....X.....C . ......D . Initially the momentum = 0, and the KE = 8. But after the collision the KE = 0. And all the particles stay together. . And another thing... aren't the laws of conservation of momentum only valids for collisions between 2 objects? If so, why does "my" momentum stays constant? . Is this what is supposed to happen? :uhh: Or is there something i don't know about it? . Thanks in advance . ps: why aren't newlines supported? i have to use dots to space the text in order to make it clearer.