A collision is short duration interaction between two bodies or more than two bodies simultaneously causing change in motion of bodies involved due to internal forces acted between them during this. Collisions involve forces (there is a change in velocity ). The magnitude of the velocity difference at impact is called the closing speed. All collisions conserve momentum. What distinguishes different types of collisions is whether they also conserve kinetic energy. Line of impact – It is the ... 3 meanings: 1. a violent impact of moving objects; crash 2. the conflict of opposed ideas, wishes, attitudes, etc 3. physics an.... Click for more definitions. Collisions are everyday events that range from a football hitting a goalpost to vehicles crashing on the road. While they may seem chaotic and unpredictable, the science behind collisions is grounded in predictable laws of motion and energy. What Is Collision : Collision is an isolated event in which a strong force acts between two or more bodies for a short time, which results in change in their velocities. In a collision , a relatively large force acts on each colliding particle for a relatively short time.