Science Explained: Kinetic Energy Difference Between Two Cars Colliding Head-On at 60 km/h vs. One Car Hitting a Wall at 60 km/h

On July 8, at the launch event for the all-electric Mercedes-Benz GLC, science communicator Li Yongle addressed the common question: "Is a head-on collision between two cars each traveling at 60 km/h equivalent to one car hitting a wall at 120 km/h?" He explained that in such a head-on collision, the total kinetic energy equals the sum of the kinetic energies of both vehicles, but this energy is shared between them. For either individual vehicle, the process of decelerating from 60 km/h to a complete stop—regarding crumple distance, deceleration rate, and peak force experienced—is essentially identical to that of the same car crashing into a rigid wall at 60 km/h. Li also clarified that in asymmetric collisions—for example, when a heavy vehicle collides head-on with a smaller car, both traveling at 60 km/h—the heavier vehicle experiences less deceleration and absorbs less impact energy due to conservation of momentum. Conversely, the lighter vehicle undergoes greater deformation and higher deceleration, resulting in more severe forces on its occupants. This principle demonstrates that, under identical speed conditions, vehicles with greater mass and more robust structural redundancy offer better occupant protection in collisions.