My awesome 4 wheel sports car hit my wooden semi-truck and the two of them collided. Luckily the two vehicles had no damage on them. The semi-truck was at rest while the sports car was traveling at a high speed toward the semi-truck. When the two vehicles collided, the sports car stopped and transferred the momentum to the semi-truck, pushing the semi truck forward. The two trucks should be going at around the same velocity because the momentum in equals the momentum out, or Pin = Pout. If the two were heading at each other at the same velocity, two would bounce off of each other and travel backwards in the opposite direction.