Head-on collision

Definition

A head-on collision is a collision where the direction of relative velocity of the two colliding bodies prior to the collision coincides with the normal direction (i.e., perpendicular direction) to the plane of contact (or tangent plane at the point of contact) of the collision.

Head-on collisions can be viewed as collisions that can be modeled in one dimension. Collisions that are not head-on collisions are sometimes termed oblique collisions.