Jessica decides to explore her understanding of momentum and energy conservation in collisions by making and testing a hypothesis. She says, "if the two trains have equal mass and initial speeds, then the total initial momentum of the system of two trains will be zero. The net momentum of the system will be conserved, and the final momentum will also be zero. So, in this case, the two trains will come to rest independent of the degree of elasticity of the collision." She runs the simulation with the masses and initial speeds of the two trains set equal for different levels of elasticity of the collision to test her hypothesis. From these simulations, Josh concludes that