Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body but may also concern a fluid. The term is derived from two Latin words: pro, meaning before or forward; and pellere, meaning to drive.
A propulsion system consists of a source of mechanical power, and a propulsor.
Armadillo Aerospace's quad rocket vehicle showing shock diamonds in the exhaust plume from its propulsion system
A turboprop-engined Tupolev Tu-95
Wheels are commonly used in ground propulsion
Transrapid 09 at the Emsland test facility in Germany
A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found in warfare and sports.
A projectile being fired from an artillery piece
Projectile and cartridge case for the huge World War II Schwerer Gustav artillery piece. Most projectile weapons use the compression or expansion of gases as their motive force.
Ball speeds of 105 miles per hour (169 km/h) have been recorded in baseball.
The Homing Overlay Experiment used a metal fan that was rolled up during launch and expanded during flight. The metal has five times as much destructive power as an explosive warhead of the same weight.
