Collisions - Perfectly Inelastic Collision

A perfectly inelastic collision is a very specific type of interaction between colliding objects. It is considered a special case of the broader category of inelastic collisions. In this type of collision, the interacting bodies physically join together. Consequently, after the collision, both objects move together with a single, common final velocity. This specific outcome leads to the maximum possible loss of kinetic energy from the system.

The exact definition from the source is: "If colliding bodies join together after collision, it is said to be a perfectly inelastic collision."

• Colliding bodies join together: The fundamental characteristic is that the objects stick to each other.
• Common final velocity: The colliding bodies move together with the same velocity after the collision.
• Loss in kinetic energy: As it is an inelastic collision, there is a loss in the kinetic energy of the system.
• Maximum K.E. loss: The loss in kinetic energy is the maximum possible in a perfectly inelastic collision.
• Not a "partially elastic" collision: The source clarifies that collisions are either perfectly elastic or inelastic (which may be partially or perfectly inelastic).

Here are practical examples that demonstrate a perfectly inelastic collision in the real world:

• Car Crash: When two vehicles collide head-on and become tangled or fused, they move as a single, combined wreck immediately after impact.
• Throwing Clay: Throwing a lump of wet clay at a wall and having it stick completely without bouncing off.
• Docking Spacecraft: A spacecraft (like a cargo module) gently and carefully links up or "docks" with the International Space Station (ISS) to move together.
• Catching a Ball: A baseball player catching a ball; the ball and the glove/hand move together at the same velocity immediately after the catch is completed.