ejections

Ejection is the act of expelling or removing something from a larger system. The term is used across disciplines to describe the forced discharge of material, objects, or people from a place, device, or situation. Ejections can be natural, engineered, or social in origin and vary widely in mechanism and consequence.

In science and engineering, ejecta refers to materials expelled from a source, such as volcanic ash, impact debris from a meteorite, or debris around an impact crater. In astronomy and planetary science, ejections can include jets and outflows from accretion disks around young stars or black holes, as well as the expulsion of material during explosive events. In fluid dynamics, ejectors or jet pumps use a high-velocity fluid to entrain and move surrounding fluids, a principle exploited in refrigeration, chemical processing, and propulsion concepts.

Astrophysical ejections may also involve gravitational interactions that eject stars or planets from a system, creating hypervelocity stars or free-floating planets.

In aviation and defense, ejection refers to mechanisms that remove a person from a vehicle in danger. Ejection seats propel the occupant out of an aircraft and deploy a parachute, a safety feature in some military aircraft.

In sports and organized activities, an ejection is the removal of a participant from a game or event for rule violations or misconduct. Officials announce the ejection and impose any associated penalties, suspensions, or disqualifications.

Overall, ejections describe a broad class of processes in which material, objects, or individuals are expelled from a system, often for safety, functional, or disciplinary reasons.