Types of Impact

Central impact occurs when two objects collide head-on with opposite velocities aligned along the line of impact. Oblique impact happens when objects collide at an angle, causing changes in both direction and velocity. The distinction determines how momentum and energy transfer during collision events.

The coefficient of restitution quantifies the ratio of relative velocity after impact to relative velocity before impact, reflecting collision elasticity. It ranges from zero to one and determines the bounciness of colliding objects. Higher values indicate greater bounce-back with original speed.

A perfectly elastic impact occurs when the coefficient of restitution equals one, meaning no kinetic energy is lost during collision. However, achieving perfect elasticity is impossible in practice because some kinetic energy is always dissipated through deformation, heat, and internal friction during the collision process.

A plastic impact occurs when the coefficient of restitution is zero, causing colliding particles to stick together and move with a common velocity after collision. Unlike elastic impacts where energy is conserved, plastic impacts result in maximum kinetic energy loss and no separation of objects.

Impact velocity, size, and shape of colliding bodies all affect the coefficient of restitution. These material and geometric properties determine how much energy is retained versus dissipated during collision, directly influencing whether an impact behaves elastically or plastically in real-world scenarios.

During any collision, kinetic energy is inevitably dissipated through deformation, heat, sound, and internal friction within the colliding bodies. This energy loss prevents perfectly elastic impacts from occurring in practice, making the coefficient of restitution always less than one in real-world scenarios.

The coefficient of restitution serves as a pivotal parameter for gauging impact bounciness and predicting post-collision behavior. Understanding this metric is essential for analyzing collision dynamics through the principle of linear impulse and momentum for a single particle, which connects velocity changes to applied forces.