We consider a set of hard point particles distributed uniformly with a specified density on the positive half-line and all initially at rest. The particle masses alternate between two values. $m$ and $M$. The particles interact via collisions that conserve energy and momentum. https://www.bekindtopets.com/super-super-Handlebar-Stem-for-the-GOTRAX-GXL-V2-Electric-Scooter-hot-choice/