1. The problem statement, all variables and given/known data In an inelastic collision, momentum is conserved but kinetic energy is not conserved. How can this be true in the situation where a car runs into the back of a stationary truck, since after the collision neither are moving and so cannot have momentum? 2. Relevant equations 3. The attempt at a solution If neither the car nor the truck is moving than the momentum must have transferred to the earth and the earth is actually moving. Although it’s mass is so large that the velocity is basically undetectable.