# Types of Impact

JoVE Core
Mechanical Engineering
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JoVE Core Mechanical Engineering
Types of Impact

### Vidéo suivante14.7: Impact: Problem Solving

Impacts can be classified into various types.

A central impact occurs when two objects collide head-on with opposite velocities aligned along the line of impact.

Oblique impact occurs when two objects collide at an angle, causing a change in direction and velocity.

The ratio of the relative velocity after and before the impact is the coefficient of restitution. It measures the elasticity of a collision and ranges from zero to one.

Factors like impact velocity, size, and shape of the colliding bodies affect the coefficient of restitution.

A perfectly elastic impact occurs when the coefficient of restitution is one, and there is no loss of kinetic energy. However, achieving perfect elasticity is impossible. During the collision, a part of kinetic energy is always lost in some form.

When the coefficient of restitution is zero, the impact is called a plastic impact, wherein the colliding particles stick together and move with a common velocity after the collision.

The coefficient of restitution determines the bounciness of an object. Higher values indicate a greater bounce-back with the original speed.

## Types of Impact

Impacts can be classified in various forms, primarily under two subgroups: central impact and oblique impact. A central impact occurs when two objects collide head-on, possessing opposite velocities aligned along the line of impact. Conversely, an oblique impact occurs when two objects collide at an angle, resulting in a modification of both direction and velocity.

The coefficient of restitution is a metric for understanding the dynamics of impacts. It quantifies the ratio of relative velocity after the impact to that before the impact, reflecting the elasticity of the collision. This coefficient ranges from zero to one, with a value of one indicating a perfectly elastic impact where no kinetic energy is lost. However, achieving absolute elasticity is unattainable, as some kinetic energy is inevitably dissipated during the collision.

Several factors influence the coefficient of restitution, including impact velocity, as well as the size and shape of the colliding bodies. When the coefficient is zero, the impact is termed a plastic impact, where colliding particles adhere together and move with a shared velocity post-collision. The coefficient of restitution essentially determines the bounce-back behavior of an object, with higher values indicating a more pronounced rebound to the original speed. In practical terms, a perfectly elastic impact remains an idealized scenario, while the coefficient of restitution serves as a pivotal parameter in gauging the impact's bounciness.